Others indeed may talk, and write, and fight about liberty, and make an outward pretence to it; but the free-thinker alone is truly free.

To be a good patriot, a man must consider his countrymen as God’s creatures, and himself as accountable for his acting towards them.

If what you mean by the word “matter” be only the unknown support of unknown qualities, it is no matter whether there is such a thing or no, since it no way concerns us; and I do not see the advantage there is in disputing about what we know not what, and we know not why.

The only things we perceive are our perceptions.

The fawning courtier and the surly squire often mean the same thing, – each his own interest.

Westward the course of empire takes its way; The four first acts already past, A fifth shall close the drama with the day: Time’s noblest offspring is the last.

But the velocities of the velocities – the second, third, fourth, and fifth velocities, etc. – exceed, if I mistake not, all human understanding...

I know what I mean by the term I and myself; and I know this immediately, or intuitively, though I do not perceive it as I perceive a triangle, a colour, or a sound.

I am old and do not suffer fools gently and if you expect me to review your work, it better meet my stringent standards for logic and science.

If a tree falls in a forest and no one is around to hear it, does it make a sound?