An Idea (n.) is a concept (or action) of the mind formed by the mind.
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An Idea (n.) is a conception, not a perception — something the mind does, not something done to it.
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An Idea (n.) of Peter in Paul's mind tells more about Paul's body than about Peter — which is why Paul can go on seeing Peter as present after Peter is dead.
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An Idea (n.) is always true in so far as it is referred to God.
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An Idea (n.) is not a silent painting on a canvas but an affirmation: it posits itself.