Conjecture as to things useful, is good; but conjecture as to what it would be useless to know, is very read more

Conjecture as to things useful, is good; but conjecture as to what it would be useless to know, is very idle.

Let us work without theorizing, 'Tis the only way to make life endurable.

Let us work without theorizing, 'Tis the only way to make life endurable.

Many things difficult to design prove easy to performance.

Many things difficult to design prove easy to performance.

It is the theory that decides what can be observed

It is the theory that decides what can be observed

If the facts don't fit the theory, change the facts.

If the facts don't fit the theory, change the facts.

Our theories of the eternal are as valuable as are those which a chick which has not broken its way read more

Our theories of the eternal are as valuable as are those which a chick which has not broken its way through its shell might form of the outside world.

A young boy is a theory, an old man is a fact.

A young boy is a theory, an old man is a fact.

An ounce of action is worth a ton of theory.

An ounce of action is worth a ton of theory.

I never once made a discovery ... I speak without exaggeration that I have constructed three thousand different theories in read more

I never once made a discovery ... I speak without exaggeration that I have constructed three thousand different theories in connection with the electric light ... Yet in only two cases did my experiments prove the truth of my theory.