Encyclopaedia Britannica, 11th Edition, "Luray Cavern" to "Mackinac Island" Volume 17, Slice 2

iv. It can have no efficacy for souls in Purgatory; penalties imposed

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by the church can only refer to the living; death dissolves them; what the pope can do for souls in Purgatory is by prayer, not by jurisdiction or the power of the keys.