Doubt is the beginning, not the end, of wisdom.
A superstition is a premature explanation that overstays its time.
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.
A tree nowhere offers a straight line or a regular curve, but who doubts that root, trunk, boughs, and leaves embody geometry?
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.
Form may be of more account than substance. A lens of ice will focus a solar beam to a blaze.
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.
No gun is perfectly true. So the marksman, that he may hit the bull's-eye, points elsewhere.
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.
Discovery begins by finding the discoverer.
When a learner, in the fullness of his powers, comes to great truths unstaled by premature familiarity, he rejoices in the lateness of his lessons.
Truth is better disengaged from error than torn from it.
Let truth be a banner big enough to hide the man who holds it up.
Evolution pays and that is why there is evolution
To render aid to the worthless is sheer waste. Rain does not freshen the Dead Sea, but only enables it to dissolve more salt.
Dumbness and silence are two different things.
Is any knowledge worthless? Try to think of an example.
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.
Error held as truth has much the effect of truth. In politics and religion this fact upsets many confident predictions.
Some young folks have wind-fall minds, prematurely detached from the tree of knowledge for a life-long sourness and pettiness.
When we try to imagine a chaos we fail. ... In its very fiber the mind is an order and refuses to build a chaos.
Ignorance may find a truth on its doorstep that erudition vainly seeks in the stars.
Degree is much: the whole Atlantic might be lukewarm and never boil us a potato.
Nothing cools so fast as undue enthusiasm. Water that has boiled freezes sooner than any other.
Educated folk keep to one another's company too much, leaving other people much like milk skimmed of its cream.
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