Page:The Prose Works of Percy Bysshe Shelley (Volume 2).djvu/297

 THE MIND.

I. is an axiom in mental philosophy, that we can think of nothing which we have not perceived. When I say that we can think of nothing, I mean, we can imagine nothing, we can reason of nothing, we can remember nothing, we can foresee nothing. The most astonishing combinations of poetry, the subtlest deductions of logic and mathematics, are no other than combinations which the intellect makes of sensations according to its own laws. A catalogue of all the thoughts of the mind, and of all their possible modifications, is a cyclopedic history of the universe.

But, it will be objected, the inhabitants of the various planets of this and other solar systems; and the existence of a Power bearing the same relation to all that we perceive and are, as what we call a cause does to what we call effect, were never subjects of sensation, and yet the laws of mind almost universally suggest, according to the