You have to know you can first. How comes later.

You have to know you can first. How comes later.

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.

There can be no theory of any account unless it corroborate with the theory of the earth.

There can be no theory of any account unless it corroborate with the theory of the earth.

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.

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

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

In theory there is no difference between theory and practice. In practice there is.

In theory there is no difference between theory and practice. In practice there is.

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.

You cannot run a business, or anything else, on a theory.

You cannot run a business, or anything else, on a theory.

Life is so unlike theory.

Life is so unlike theory.