We are what we do, not what we think.  Only the interactions count.

Iain Banks, The Player of Games

A man's worth is just the worth of that which he pursues....Be upright either by nature or by correction.

Contemplate the courses of the stars, as one should do that revolves along with them. Consider also without ceasing the changes of elements, one into another. Speculations upon such things cleanse away the filth of this earthly life.

Marcus Aurelius, Meditations (Book 7)

The cumulative increase of knowledge in science has no parallel in ethics or politics. 

John Grey, as quoted by Casey Cep in "Why Are Americans Still Uncomfortable with Atheism" in the New Yorker.

 

The existence of conscious minds and their access to the evident truths of ethics and mathematics are among the data that a theory of the world and our place in it has yet to explain.... A satisfying explanation would show that the realization of these possibilities was not vanishingly improbable but a significant likelihood given the laws of nature and the composition of the universe.

Thomas Nagel, Mind & Cosmos