PART III.

OF THE SUBDIVISION OF PHYSICS INTO DISTINCT BRANCHES, AND THEIR MUTUAL RELATIONS.

CHAP. I.

Of the Phenomena of Force, and of the Constitution of Natural Bodies. 221

CHAP. II.

Of the Communication of Motion through Bodies.--Of Sound and Light. 246

CHAP. III.

Of Cosmical Phenomena. 265

CHAP. IV.

Of the Examination of the material Constituents of the World. 290

CHAP. V.

Of the Imponderable Forms of Matter. 310

CHAP. VI.

Of the Causes of the actual rapid Advance of the Physical Sciences compared with their Progress at an earlier Period. 347

“In primis, hominis est propria VERI inquisitio atque investigatio. Itaque cum sumus negotiis necessariis, curisque vacui, tum avemus aliquid videre, audire, ac dicere, cognitionemque rerum, aut occultarum aut admirabilium, ad benè beatéque vivendum necessariam ducimus;--ex quo intelligitur, quod VERUM, simplex, sincerumque sit, id esse naturæe hominis aptissimum. Huic veri videndi cupiditati adjuncta est appetitio quædam principatûs, ut nemini parere animus benè a naturâ informatus velit, nisi præcipienti, aut docenti, aut utilitatis causa justè et legitimè imperanti: ex quo animi magnitudo existit, et humanararum rerum contemtio.”

CICERO, DE OFFICIIS, Lib. 1. § 13.

Before all other things, man is distinguished by his pursuit and investigation of TRUTH. And hence, when free from needful business and cares, we delight to see, to hear, and to communicate, and consider a knowledge of many admirable and abstruse things necessary to the good conduct and happiness of our lives: whence it is clear that whatsoever is TRUE, simple, and direct, the same is most congenial to our nature as men. Closely allied with this earnest longing to see and know the truth, is a kind of dignified and princely sentiment which forbids a mind, naturally well constituted, to submit its faculties to any but those who announce it in precept or in doctrine, or to yield obedience to any orders but such as are at once just, lawful, and founded on utility. From this source spring greatness of mind and contempt of worldly advantages and troubles.

PRELIMINARY DISCOURSE ON THE STUDY OF NATURAL PHILOSOPHY.