We must certainly seek some new system on this head, and there plainly is none beside what I have proposed.

If ideas be particular in their nature, and at the same time finite in their number, it is only by custom they can become general in their representation, and contain an infinite number of other ideas under them.
Before I leave this subject I shall employ the same principles to explain that distinction of reason, which is so much talked of, and is so little understood, in the schools.

Of this kind is the distinction betwixt figure and the body figured; motion and the body moved.

The difficulty of explaining this distinction arises from the principle above explained, that all ideas, which are different, are separable.

For it follows from thence, that if the figure be different from the body, their ideas must be separable as well as distinguishable: if they be not different, their ideas can neither be separable nor distinguishable.
What then is meant by a distinction of reason, since it implies neither a difference nor separation.
To remove this difficulty we must have recourse to the foregoing explication of abstract ideas.