Part 15

Essential parts of Berkeley’s analysis are explained by Voltaire, in his _Élémens de la Philosophie de Newton_. The following from that work is here given on its own account, and also as a prominent recognition of the new doctrine in France, within thirty years from its first promulgation:—

“Il faut absolument conclure de tout ceci, que les distances, les grandeurs, les situations, ne sont pas, à proprement parler, des choses visibles, c’est-à-dire, ne sont pas les objets propres et immédiats de la vue. L’objet propre et immédiat de la vue n’est autre chose que la lumière colorée: tout le reste, nous ne le sentons qu’à la longue et par expérience. Nous apprenons à voir précisément comme nous apprenons à parler et à lire. La différence est, que l’art de voir est plus facile, et que la nature est également à tous notre maître.

“Les jugements soudains, presque uniformes, que toutes nos âmes, à un certain âge, portent des distances, des grandeurs, des situations, nous font penser qu’il n’y a qu’à ouvrir les yeux pour voir la manière dont nous voyons. On se trompe; il y faut le secours des autres sens. Si les hommes n’avaient que le sens de la vue, ils n’auraient aucun moyen pour connaître l’étendue en longueur, largeur et profondeur; et un pur esprit ne la connaîtrait pas peutêtre, à moins que Dieu ne la lui révélât. Il est très difficile de séparer dans notre entendement l’extension d’un objet d’avec les couleurs de cet objet. Nous ne voyons jamais rien que d’étendu, et de là nous sommes tous portés à croire que nous voyons en effet l’étendue.” (_Élémens de la Philos. de Newton_, Seconde Partie, ch. 7.)

Condillac, in his _Essais sur l’Origine des Connaissances Humaines_ (Part I. sect. 6), published in 1746, combats Berkeley’s _New Theory_, and maintains that an extension exterior to the eye is immediately discernible by sight; the eye being naturally capable of judging at once of figures, magnitudes, situations, and distances. His reasonings in support of this “prejudice,” as he afterwards allowed it to be, may be found in the section entitled “De quelques jugemens qu’on a attribués à l’âme sans fondement, ou solution d’un problème de métaphysique.” Here Locke, Molyneux, Berkeley, and Voltaire are criticised, and Cheselden’s experiment is referred to. Condillac’s subsequent recantation is contained in his _Traité des Sensations_, published in 1754, and in his _L’Art de Penser_. In the _Traité des Sensations_ (Troisième Partie, ch. 3, 4, 5, 6, 7, 8, &c.) the whole question is discussed at length, and Condillac vindicates what he allows must appear a marvellous paradox to the uninitiated—that we only gradually learn to see, hear, smell, taste, and touch. He argues in particular that the eye cannot originally perceive an extension that is beyond itself, and that perception of trinal space is due to what we experience in touch.

Voltaire and Condillac gave currency to the _New Theory_ in France, and it soon became a commonplace with D’Alembert, Diderot, Buffon, and other French philosophers. In Germany we have allusions to it in the Berlin Memoirs and elsewhere; but, although known by name, if not in its distinctive principle and latent idealism, it has not obtained the consideration which its author’s developed theory of the material as well as the visible world has received. The Kantian _a priori_ criticism of our cognition of Space, and of our mathematical notions, subsequently indisposed the German mind to the _a posteriori_ reasoning of Berkeley’s _Essay_.

Its influence is apparent in British philosophy. The following passages in Hartley’s _Observations on Man_, published in 1749, illustrate the extent to which some of the distinctive parts of the new doctrine were at that time received by an eminent English psychologist:—

“Distance is judged of by the quantity of motion, and figure by the relative quantity of distance.... And, as the sense of sight is much more extensive and expedite than feeling, we judge of tangible qualities chiefly by sight, which therefore may be considered, agreeably to Bishop Berkeley’s remark, as a philosophical language for the ideas of feeling; being, for the most part, an adequate representative of them, and a language common to all mankind, and in which they all agree very nearly, after a moderate degree of experience.

“However, if the informations from touch and sight disagree at any time, we are always to depend upon touch, as that which, according to the usual ways of speaking upon these subjects, is the true representation of the essential properties, i.e. as the earnest and presage of what other tangible impressions the body under consideration will make upon our feeling in other circumstances; also what changes it will produce in other bodies; of which again we are to determine by our feeling, if the visual language should not happen to correspond to it exactly. And it is from this difference that we call the touch the reality, light the representative—also that a person born blind may foretell with certainty, from his present tangible impressions, what others would follow upon varying the circumstances; whereas, if we could suppose a person to be born without feeling, and to arrive at man’s estate, he could not, from his present visible impressions, judge what others would follow upon varying the circumstances. Thus the picture of a knife, drawn so well as to deceive his eye, would not, when applied to another body, produce the same change of visible impressions as a real knife does, when it separates the parts of the body through which it passes. But the touch is not liable to these deceptions. As it is therefore the fundamental source of information in respect of the essential properties of matter, it may be considered as our first and principal key to the knowledge of the external world.” (Prop. 30.)

In other parts of Hartley’s book (e.g. Prop. 58) the relation of our visual judgments of magnitude, figure, motion, distance, and position to the laws of association is explained, and the associating circumstances by which these judgments are formed are enumerated in detail.

Dr. Porterfield of Edinburgh, in his _Treatise on the Eye, or the Manner and Phenomena of Vision_ (Edinburgh, 1759), is an exception to the consent which the doctrine had then widely secured. He maintains, in opposition to Berkeley, that “the judgments we form of the situation and distance of visible objects, depend not on custom and experience, but on original instinct, to which mind is subject in our embodied state(279).”

Berkeley’s Theory of Vision, in so far as it resolves our visual perceptions of distance into interpretation of arbitrary signs, received the qualified approbation of Reid, in his _Inquiry into the Human Mind on the Principles of Common Sense_ (1764). He criticises it in the _Inquiry_, where the doctrine of visual signs, of which Berkeley’s whole philosophy is a development, is accepted, and to some extent applied. With Reid it is divorced, however, from the Berkeleian conception of the material world, although the Theory of Vision was the seminal principle of Berkeley’s Theory of Matter(280).

This Theory of Matter was imperfectly conceived and then rejected by Reid and his followers, while the New Theory of Vision obtained the general consent of the Scottish metaphysicians. Adam Smith refers to it in his _Essays_ (published in 1795) as “one of the finest examples of philosophical analysis that is to be found either in our own or in any other language.” Dugald Stewart characterises it in his _Elements_ as “one of the most beautiful, and at the same time one of the most important theories of modern philosophy.” “The solid additions,” he afterwards remarks in his _Dissertation_, “made by Berkeley to the stock of human knowledge, were important and brilliant. Among these the first place is unquestionably due to his _New Theory of Vision_, a work abounding with ideas so different from those commonly received, and at the same time so profound and refined, that it was regarded by all but a few accustomed to deep metaphysical reflection, rather in the light of a philosophical romance than of a sober inquiry after truth. Such, however, has since been the progress and diffusion of this sort of knowledge, that the leading and most abstracted doctrines contained in it form now an essential part of every elementary treatise on optics, and are adopted by the most superficial smatterers in science as fundamental articles of their faith.” The _New Theory_ is accepted by Thomas Brown, who proposes (_Lectures_, 29) to extend the scope of its reasonings. With regard to perceptions of sight, Young, in his _Lectures on Intellectual Philosophy_ (p. 102), says that “it has been universally admitted, at least since the days of Berkeley, that many of those which appear to us at present to be instantaneous and primitive, can yet be shewn to be acquired; that most of the adult perceptions of sight are founded on the previous information of touch; that colour can give us no conception originally of those qualities of bodies which produce it in us; and that primary vision gives us no notion of distance, and, as I believe, no notion of magnitude.” Sir James Mackintosh, in his _Dissertation_, characterises the _New Theory of Vision_ as “a great discovery in Mental Philosophy.” “Nothing in the compass of inductive reasoning,” remarks Sir William Hamilton (Reid’s _Works_, p. 182, note), “appears more satisfactory than Berkeley’s demonstration of the necessity and manner of our learning, by a slow process of observation and comparison alone, the connexion between the perceptions of vision and touch, and, in general, all that relates to the distance and magnitude of external things(281).”

The New Theory of Vision has in short been generally accepted, so far as it was understood, alike by the followers of Hartley and by the associates and successors of Reid. Among British psychologists, it has recommended itself to rationalists and sensationalists, to the advocates of innate principles, and to those who would explain by accidental association what their opponents attribute to reason originally latent in man. But this wide conscious assent is I think chiefly confined to the proposition that distance is invisible, and hardly reaches the deeper implicates of the theory, on its extension to all the senses, leading to a perception of the final unity of the natural and the supernatural, and the ultimate spirituality of the universe(282).

Dedication

TO THE RT. HON. SIR JOHN PERCIVALE, BART.(283),

ONE OF HER MAJESTY’S MOST HONOURABLE PRIVY COUNCIL

IN THE KINGDOM OF IRELAND.

Sir,

I could not, without doing violence to myself, forbear upon this occasion to give some public testimony of the great and well-grounded esteem I have conceived for you, ever since I had the honour and happiness of your acquaintance. The outward advantages of fortune, and the early honours with which you are adorned, together with the reputation you are known to have amongst the best and most considerable men, may well imprint veneration and esteem on the minds of those who behold you from a distance. But these are not the chief motives that inspire me with the respect I bear you. A nearer approach has given me the view of something in your person infinitely beyond the external ornaments of honour and estate. I mean, an intrinsic stock of virtue and good sense, a true concern for religion, and disinterested love of your country. Add to these an uncommon proficiency in the best and most useful parts of knowledge; together with (what in my mind is a perfection of the first rank) a surpassing goodness of nature. All which I have collected, not from the uncertain reports of fame, but from my own experience. Within these few months that I have the honour to be known unto you, the many delightful hours I have passed in your agreeable and improving conversation have afforded me the opportunity of discovering in you many excellent qualities, which at once fill me with admiration and esteem. That one at those years, and in those circumstances of wealth and greatness, should continue proof against the charms of luxury and those criminal pleasures so fashionable and predominant in the age we live in; that he should preserve a sweet and modest behaviour, free from that insolent and assuming air so familiar to those who are placed above the ordinary rank of men; that he should manage a great fortune with that prudence and inspection, and at the same time expend it with that generosity and nobleness of mind, as to shew himself equally remote from a sordid parsimony and a lavish inconsiderate profusion of the good things he is intrusted with—this, surely, were admirable and praiseworthy. But, that he should, moreover, by an impartial exercise of his reason, and constant perusal of the sacred Scriptures, endeavour to attain a right notion of the principles of natural and revealed religion; that he should with the concern of a true patriot have the interest of the public at heart, and omit no means of informing himself what may be prejudicial or advantageous to his country, in order to prevent the one and promote the other; in fine, that, by a constant application to the most severe and useful studies, by a strict observation of the rules of honour and virtue, by frequent and serious reflections on the mistaken measures of the world, and the true end and happiness of mankind, he should in all respects qualify himself bravely to run the race that is set before him, to deserve the character of great and good in this life, and be ever happy hereafter—this were amazing and almost incredible. Yet all this, and more than this, SIR, might I justly say of you, did either your modesty permit, or your character stand in need of it. I know it might deservedly be thought a vanity in me to imagine that anything coming from so obscure a hand as mine could add a lustre to your reputation. But, I am withal sensible how far I advance the interest of my own, by laying hold on this opportunity to make it known that I am admitted into some degree of intimacy with a person of your exquisite judgment. And, with that view, I have ventured to make you an address of this nature, which the goodness I have ever experienced in you inclines me to hope will meet with a favourable reception at your hands. Though I must own I have your pardon to ask, for touching on what may possibly be offensive to a virtue you are possessed of in a very distinguishing degree. Excuse me, SIR, if it was out of my power to mention the name of SIR JOHN PERCIVALE without paying some tribute to that extraordinary and surprising merit whereof I have so clear and affecting an idea, and which, I am sure, cannot be exposed in too full a light for the imitation of others,

Of late I have been agreeably employed in considering the most noble, pleasant, and comprehensive of all the senses(284). The fruit of that (labour shall I call it or) diversion is what I now present you with, in hopes it may give some entertainment to one who, in the midst of business and vulgar enjoyments, preserves a relish for the more refined pleasures of thought and reflexion. My thoughts concerning Vision have led me into some notions so far out of the common road(285) that it had been improper to address them to one of a narrow and contracted genius. But, you, SIR, being master of a large and free understanding, raised above the power of those prejudices that enslave the far greater part of mankind, may deservedly be thought a proper patron for an attempt of this kind. Add to this, that you are no less disposed to forgive than qualified to discern whatever faults may occur in it. Nor do I think you defective in any one point necessary to form an exact judgment on the most abstract and difficult things, so much as in a just confidence of your own abilities. And, in this one instance, give me leave to say, you shew a manifest weakness of judgment. With relation to the following _Essay_, I shall only add that I beg your pardon for laying a trifle of that nature in your way, at a time when you are engaged in the important affairs of the nation, and desire you to think that I am, with all sincerity and respect,

SIR,

Your most faithful and most humble servant,

GEORGE BERKELEY.

An Essay Towards A New Theory Of Vision

1. My design is to shew the manner wherein we perceive by Sight the Distance, Magnitude, and Situation of objects: also to consider the difference there is betwixt the ideas of Sight and Touch, and whether there be any idea common to both senses(286).

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2. It is, I think, agreed by all that Distance, of itself and immediately, cannot be seen(287). For, distance(288) being a line directed endwise to the eye, it projects only one point in the fund of the eye, which point remains invariably the same, whether the distance be longer or shorter(289).

3. I find it also acknowledged that the estimate we make of the distance of objects considerably remote is rather an act of judgment grounded on experience than of sense. For example, when I perceive a great number of intermediate objects, such as houses, fields, rivers, and the like, which I have experienced to take up a considerable space, I thence form a judgment or conclusion, that the object I see beyond them is at a great distance. Again, when an object appears faint and small which at a near distance I have experienced to make a vigorous and large appearance, I instantly conclude it to be far off(290). And this, it is evident, is the result of experience; without which, from the faintness and littleness, I should not have inferred anything concerning the distance of objects.

4. But, when an object is placed at so near a distance as that the interval between the eyes bears any sensible proportion to it(291), the opinion of speculative men is, that the two optic axes (the fancy that we see only with one eye at once being exploded), concurring at the object, do there make an angle, by means of which, according as it is greater or lesser, the object is perceived to be nearer or farther off(292).

5. Betwixt which and the foregoing manner of estimating distance there is this remarkable difference:—that, whereas there was no apparent _necessary_ connexion between small distance and a large and strong appearance, or between great distance and a little and faint appearance, there appears a very _necessary_ connexion between an obtuse angle and near distance, and an acute angle and farther distance. It does not in the least depend upon experience, but may be evidently known by any one before he had experienced it, that the nearer the concurrence of the optic axes the greater the angle, and the remoter their concurrence is, the lesser will be the angle comprehended by them.

6. There is another way, mentioned by optic writers, whereby they will have us judge of those distances in respect of which the breadth of the pupil hath any sensible bigness. And that is the greater or lesser divergency of the rays which, issuing from the visible point, do fall on the pupil—that point being judged nearest which is seen by most diverging rays, and that remoter which is seen by less diverging rays, and so on; the apparent distance still increasing, as the divergency of the rays decreases, till at length it becomes infinite, when the rays that fall on the pupil are to sense parallel. And after this manner it is said we perceive distance when we look only with one eye.

7. In this case also it is plain we are not beholden to experience: it being a certain necessary truth that, the nearer the direct rays falling on the eye approach to a parallelism, the farther off is the point of their intersection, or the visible point from whence they flow.

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8. (293)Now, though the accounts here given of perceiving _near_ distance by sight are received for true, and accordingly made use of in determining the apparent places of objects, they do nevertheless seem to me very unsatisfactory, and that for these following reasons:—

9. [_First_(294),] It is evident that, when the mind perceives any idea not immediately and of itself, it must be by the means of some other idea. Thus, for instance, the passions which are in the mind of another are of themselves to me invisible. I may nevertheless perceive them by sight; though not immediately, yet by means of the colours they produce in the countenance. We often see shame or fear in the looks of a man, by perceiving the changes of his countenance to red or pale.

10. Moreover, it is evident that no idea which is not itself perceived can be to me the means of perceiving any other idea. If I do not perceive the redness or paleness of a man’s face themselves, it is impossible I should perceive by them the passions which are in his mind.

11. Now, from sect. ii., it is plain that distance is in its own nature imperceptible, and yet it is perceived by sight(295). It remains, therefore, that it be brought into view by means of some other idea, that is itself immediately perceived in the act of vision.

12. But those lines and angles, by means whereof some men(296) pretend to explain the perception(297) of distance, are themselves not at all perceived; nor are they in truth ever thought of by those unskilful in optics. I appeal to any one’s experience, whether, upon sight of an object, he computes its distance by the bigness of the angle made by the meeting of the two optic axes? or whether he ever thinks of the greater or lesser divergency of the rays which arrive from any point to his pupil? nay, whether it be not perfectly impossible for him to perceive by sense the various angles wherewith the rays, according to their greater or lesser divergence, do fall on the eye? Every one is himself the best judge of what he perceives, and what not. In vain shall any man(298) tell me, that I perceive certain lines and angles, which introduce into my mind the various ideas of distance, so long as I myself am conscious of no such thing.

13. Since therefore those angles and lines are not themselves perceived by sight, it follows, from sect. x., that the mind does not by them judge of the distance of objects.

14. [_Secondly_(299),] The truth of this assertion will be yet farther evident to any one that considers those lines and angles have no real existence in nature, being only an hypothesis framed by the mathematicians, and by them introduced into optics, that they might treat of that science in a geometrical way.

15. The [_third_ and(300)] last reason I shall give for rejecting that doctrine is, that though we should grant the real existence of those optic angles, &c., and that it was possible for the mind to perceive them, yet these principles would not be found sufficient to explain the phenomena of distance, as shall be shewn hereafter.

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16. Now it being already shewn(301) that distance is _suggested_(302) to the mind, by the mediation of some other idea which is itself perceived in the act of seeing, it remains that we inquire, what ideas or sensations there be that attend vision, unto which we may suppose the ideas of distance are connected, and by which they are introduced into the mind.

And, _first_, it is certain by experience, that when we look at a near object with both eyes, according as it approaches or recedes from us, we alter the disposition of our eyes, by lessening or widening the interval between the pupils. This disposition or turn of the eyes is attended with a sensation(303), which seems to me to be that which in this case brings the idea of greater or lesser distance into the mind.