An _idea_, according to his definition, (which he says is precise and accurate,) is, "That _perception_ of a real object which _is raised_ in the mind by the power of _memory_." But among the real objects from which memory may raise ideas, he includes the workings of the mind itself, or whatever we remember of our former passions, emotions, thoughts, or designs.

Such a definition, he imagines, might have saved Locke, Berkley, and their followers, from much vain speculation; for with the ideal systems of these philosophers, or with those of Aristotle and Des Cartes, he by no means coincides.

This author says, "As ideas are the chief materials employed in reasoning and reflecting, it is of consequence that their nature and differences be understood.

It appears now that ideas may be distinguished into three kinds: first, Ideas derived from original perceptions, properly termed _ideas of memory_; second, Ideas communicated _by language_ or other signs; and third, Ideas _of imagination_.

These ideas differ from each other in many respects; but chiefly in respect to their _proceeding from different causes_.