If the facts don't fit the theory, change the facts.
An ounce of action is worth a ton of theory.
Thought and theory must precede all salutary action; yet action is nobler in itself than either thought or theory
There is a theory which states that if ever for any reason anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.
If Darwin's theory should be true, it will not degrade man; it will simply raise the whole animal world into dignity, leaving man as far in advance as he is at present
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.
Theory helps us to bear our ignorance of facts
The theory seems to be that as long as a man is a failure he is one of God's children, but that as soon as he succeeds he is taken over by the Devil.
Knowledge is not a series of self consistent theories that converges towards an ideal view; it is rather an ever increasing ocean of mutually incompatible (and perhaps even incommensurable) alternatives, each single theory, each fairy tale, each myth
It is the theory that decides what can be observed
Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory nor the problem which it was intended to solve
He who loves practice without theory is like the sailor who boards ship without a rudder and compass and never knows where he may cast.
How empty is theory in the presence of fact
First, you know, a new theory is attacked as absurd; then it is admitted to be true, but obvious and insignificant; finally it is seen to be so important that its adversaries claim that they themselves discovered it
The truth of a theory is in your mind, not in your eyes.
We are all agreed that your theory is crazy. The question which divides us is whether it is crazy enough to have a chance of being correct. My own feeling is that it is not crazy enough.
The popularity of conspiracy theories is explained by people's desire to believe that there is - some group of folks who know what they're doing
Louis Pasteur's theory of germs is ridiculous fiction
If the Confederacy fails, there should be written on its tombstone: Died of a Theory.
It is often stated that of all the theories proposed in this century, the silliest is quantum theory. In fact, some say that the only thing that quantum theory has going for it is that it is unquestionably correct.
The theory that can absorb the greatest number of facts, and persist in doing so, generation after generation, through all changes of opinion and detail, is the one that must rule all observation.
It is a test of true theories not only to account for but to predict phenomena
It is the theory that decides what we can observe.
Einstein explained his theory to me every day, and on my arrival I was fully convinced that he understood it.
Theory may raise your hopes but practice raises your income