Be not astonished at new ideas; for it is well known to you that a thing does not therefore cease to be true because it is not accepted by many.
Self-complacency is pleasure accompanied by the idea of oneself as cause.
He who would distinguish the true from the false must have an adequate idea of what is true and false.
The idea, which constitutes the actual being of the human mind, is not simple, but compounded of a great number of ideas.
Love is nothing but joy accompanied with the idea of an eternal cause.
To comprehend an idea, a person must simultaneously accept it as true. Conscious analysis - which, depending on the idea, may occur almost immediately or with considerable effort - allows the mind to reject what it intially accepted as fact.
The order and connection of ideas is the same as the order and connection of things.
He who has a true idea, knows at that same time that he has a true idea, nor can he doubt concerning the truth of the thing.
Love is pleasure accompanied by the idea of an external cause, and hatred pain accompanied by the idea of an external cause.