The only roads of enquiry there are to think of: one, that it is and that it is not possible for it not to be, this is the path of persuasion (for truth is its companion); the other, that it is not and that it must not be - this I say to you is a path wholly unknowable.

Gaze steadfastly at things which, though far away, are yet present to the mind.

It is indifferent to me where I am to begin, for there shall I return again.

Being alone is and nothing is altogether not.

You must learn all things, both the unshaken heart of persuasive truth, and the opinions of mortals in which there is no true warranty.

Every thing is of the nature of no thing.

Let reason alone decide.