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

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

Doubt is the beginning, not the end, of wisdom.

When we try to imagine a chaos we fail. ... In its very fiber the mind is an order and refuses to build a chaos.

Error held as truth has much the effect of truth. In politics and religion this fact upsets many confident predictions.

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.

Nature is full of by-ends. A moth feeds on a petal, in a moment the pollen caught on its breast will be wedding this blossom to another in the next county.