Is any knowledge worthless? Try to think of an example.

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

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

Dumbness and silence are two different things.

A man's own addition to what he learns is cement to bind an otherwise loose heap of stones into a structure of unity, strength, and use.

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.

Boundaries which mark off one field of science from another are purely artificial, are set up only for temporary convenience. Let chemists and physicists dig deep enough, and they reach common ground.