If in life we are surrounded by death, so too in the health of our intellect by madness.

A man's thinking goes on within his consciousness in a seclusion in comparison with which any physical seclusion is an exhibition to public view.

All philosophy is a 'critique of language' (though not in Mauthner's sense). It was Russell who performed the service of showing that the apparent logical form of a proposition need not be its real one.

The truth of the thoughts that are here set forth seems to me unassailable and definitive. I therefore believe myself to have found, on all essential points, the final solution of the problems. And if I am not mistaken in this belief, then the second thing in which the value of this work consists is that it shows how little is achieved when these problems are solved.

Language disguises thought.

Never stay up on the barren heights of cleverness, but come down into the green valleys of silliness.

The aspects of things that are most important for us are hidden because of their simplicity and familiarity. (One is unable to notice something because it is always before one’s eyes.) The real foundations of his enquiry do not strike a man at all