Never try to discourage thinking, for you are sure to succeed.

Men fear thought as they fear nothing else on earth -- more than ruin, more even than death. Thought is subversive and revolutionary, destructive and terrible, thought is merciless to privilege, established institutions, and comfortable habits; thought is anarchic and lawless, indifferent to authority, careless of the well-tried wisdom of the ages. Thought looks into the pit of hell and is not afraid ... Thought is great and swift and free, the light of the world, and the chief glory of man.

Thinking you know when in fact you don't is a fatal mistake, to which we are all prone

Thought is subversive and revolutionary, destructive and terrible, Thought is merciless to privilege, established institutions, and comfortable habit. Thought is great and swift and free.

Is man what he seems to the astronomer, a tiny lump of impure carbon and water impotently crawling on a small and unimportant planet? Or is he what he seem to Hamlet? Or is he both at once?

People are zealous for a cause when they are not quite positive that it is true