A superstition is a premature explanation that overstays its time.

Let truth be a banner big enough to hide the man who holds it up.

A tree nowhere offers a straight line or a regular curve, but who doubts that root, trunk, boughs, and leaves embody geometry?

Ignorance may find a truth on its doorstep that erudition vainly seeks in the stars.

They will listen with both ears to what is said by the men just a step or two ahead of them, who stand nearest to them, and within arm's reach. A guide ceases to be of any use when he strides so far ahead as to be hidden by the curvature of the earth.

We despair of changing the habits of men, still we would alter institutions, the habits of millions of men.

To render aid to the worthless is sheer waste. Rain does not freshen the Dead Sea, but only enables it to dissolve more salt.