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.

Ten builders rear an arch, each in turn lifting it higher; but it is the tenth man, who drops in the keystone, who hears our huzzas.

A calculating engine is one of the most intricate forms of mechanism, a telegraph key one of the simplest. But compare their value.

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

Form may be of more account than substance. A lens of ice will focus a solar beam to a blaze.

Degree is much: the whole Atlantic might be lukewarm and never boil us a potato.

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