I am an enthusiast, but not a crank in the sense that I have some pet theories as to the proper construction of a flying machine. I wish to avail myself of all that is already known and then, if possible, add my mite to help on the future worker who will attain final success.

I wouldn't have thought that a wrong theory should lead us to understand better the ordinary quantum field theories or to have new insights about the quantum states of black holes.

Academics love to make theories about a body of work, but each book consumes the writer and is the sum of his or her world.

Before I married, I had three theories about raising children and no children. Now, I have three children and no theories.

Before I got married I had six theories about bringing up children; now I have six children, and no theories.

The system becomes more coherent as it is further extended. The elements which we require for explaining a new class of facts are already contained in our system. In false theories, the contrary is the case.

It is a test of true theories not only to account for but to predict phenomena.

I am more fond of achieving than striving. My theories must prove to be facts or be discarded as worthless. My efforts must soon be crowned with success, or discontinued.

In art, theories are as useful as a doctor's prescription; one must be sick to believe them.

Other psychological theories say a good deal about compensation.

Genetic theories, I gather, have been cherished academically with detachment.

In my opinion, assassination theories will continue to revolve around these assassinations as they have around several other significant assassinations in American history. The assassination of President Lincoln comes to mind.

In other words, unlike some people with new theories, we will go out, we'll go into a school and we get products and the products are evaluated, whether it's by teachers or others. The scores are quantified and then we compare performances.

Many writers upon the science of political economy have declared that it is the duty of a nation first to encourage the creation of wealth; and second, to direct and control its distribution. All such theories are delusive.

Facts do not speak for themselves. They speak for or against competing theories. Facts divorced from theories or visions are mere isolated curiosities.