For otherwise we might have supposed the fact too evident to need mention.
Imagination is the single source of the new, the one mainspring of psychical advance; reason, like a balance-wheel, only keeping the action regular.

For reason is but the touchstone of experience, our own, inherited, or acquired from others.

It compares what we imagine with what we know, and gives us answer in terms of the here and the now, which we call the actual.

But the actual is really nothing but the local.

It does not mark the limits of the possible.
That imagination has been the moving spirit of the psychical world is evident, whatever branch of human thought we are pleased to examine.