The first time I came to the Comedy Festival some nutcase shot a bunch of people in Tasmania. I thought, 'Oh, that's just Tasmania.' The second time I came, some nut shot up Columbine High School. Now I'm here again, and another nut just shot up a high school in Minnesota. If you can't see the connection between me playing the Comedy Festival and mass murder, you're no good at conspiracy theories.

The utmost abstractions are the true weapons with which to control our thought of concrete fact.

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

It is better to emit a scream in the shape of a theory than to be entirely insensible to the jars and incongruities of life and take everything as it comes in a forlorn stupidity.

Theory helps us to bear our ignorance of facts.

It is only theory that makes men completely incautious.

Theory helps us bear our ignorance of facts.

A theory must be tempered with reality.

Grey is the color of all theory.

Whether or not you can observe a thing depends upon the theory you use. It is the theory which decides what can be observed.

For every fact there is an infinity of hypotheses. The more you look the more you see.

It is so much easier to talk of poverty than to think of the poor, to argue the rights of capital than to see its results. Pretty soon we come to think of the theories and abstract ideas as things in themselves.

All theory, my friend, is grey, But green is life's glad golden tree.

To be sure, theory is useful. But without warmth of heart and without love it bruises the very ones it claims to save.

In theory, there is nothing to hinder our following what we are taught, but in life there are many things to draw us aside.

The astonishment of life is the absence of any appearances of reconciliation between the theory and the practice of life.

It is a capital mistake to theorize before one has data.

Professors in every branch of the sciences prefer their own theories to truth; the reason is that their theories are private property, but truth is common stock.

Your theory is crazy, but it's not crazy enough to be true.

No theory is good except on condition that one use it to go beyond.