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

We cannot observe external things without some degree of Thought; nor can we reflect upon our Thoughts, without being influenced in the course of our reflection by the Things which we have observed.

Every failure is a step to success.

Fundamental ideas are not a consequence of experience, but a result of the particular constitution and activity of the mind, which is independent of all experience in its origin, though constantly combined with experience in its exercise.

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

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.

Hence no force, however great, can stretch a cord, however fine, into a horizontal line which is accurately straight: there will always be a bending downwards.

The question undoubtedly is or soon will be not whether or no we shall employ notation in chemistry but whether we shall use a bad and incongruous or a consistent and regular notation.

Geometry in every proposition speaks a language which experience never dares to utter and indeed of which she but halfway comprehends the meaning.

Prudence supposes the value of the end to be assumed, and refers only to the adaptation of the means. It is the relation of right means for given ends.

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

In the little hall leading to it was a rack holding various Socialist or radical newspapers, tracts, and pamphlets in very small print and on very bad paper. The subjects treated were technical Marxist theories.

It is always incorrect to assume you can know what someone's moral convictions are based on their philosophical theories.

Some of you may have been hoping that today I would speak about Lucien Bouchard's latest economic theories. But I have decided to spare him for the time being: after all, he is a man.

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.

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.

Theories of evolution must provide for the creative acts which brought such theories into existence.

The overwhelming majority of theories are rejected because they contain bad explanations, not because they fail experimental tests.

As a rule we disbelieve all the facts and theories for which we have no use.

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

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

I know my theories and findings are hard for you to accept because they are so original and extraordinary.

The theories of the major philosophers of the 18th century secular enlightenment were biblical and theological in spite of themselves.

The credit which the apparent conformity with recognized scientific standards can gain for seemingly simple but false theories may, as the present instance shows, have grave consequences.

Theories pass. The frog remains.

The progress of science is strewn, like an ancient desert trail, with the bleached skeleton of discarded theories which once seemed to possess eternal life.

And the continuity of our science has not been affected by all these turbulent happenings, as the older theories have always been included as limiting cases in the new ones.

Other psychological theories say a good deal about compensation.

I think the point to be understood is that we're all different. I've never been a fan of theories of acting. I didn't go to drama school, so I was never put through a training that was limited by someone saying, 'This is the way you should act.'

The egoism which enters into our theories does not affect their sincerity; rather, the more our egoism is satisfied, the more robust is our belief.

Theories are patterns without value. What counts is action.

We do not talk - we bludgeon one another with facts and theories gleaned from cursory readings of newspapers, magazines and digests.

Philosophical theories or ideas, as points of view, instruments of criticism, may help us to gather up what might otherwise pass unregarded by us.

Theories crumble, but good observations never fade.

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

Theories of love are found in the works of scientists, philosophers, and theologians.

Our best theories are not only truer than common sense, they make more sense than common sense.

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.

No religious position is loyally served by refusing to consider annoying theories which may well turn out to be facts.

The Secret Doctrine is the common property of the countless millions of men born under various climates, in times with which History refuses to deal, and to which esoteric teachings assign dates incompatible with the theories of Geology and Anthropology.

We shall suffer no attachment to literature, no taste for abstract discussion, no love of purely intellectual theories, to seduce us from our devotion to the cause of the oppressed, the down trodden, the insulted and injured masses of our fellow men.

I believe without exception that theory follows practice. Whenever there is a conflict between theory and practice, theory is wrong. As far as I'm concerned, we make theories for what people have done.

The artist discards all theories, both his own and those of others. He forgets everything when he is in front of his canvas.

I think philosophers can do things akin to theoretical scientists, in that, having read about empirical data, they too can think of what hypotheses and theories might account for that data. So there's a continuity between philosophy and science in that way.

I listen to other guitar players, yeah. It gives me new concepts and shows me where the instrument is going for the future and it is going some places. There are some musicians who are really putting out a good vibe with new theories. I try and keep up.

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

Every theory presented as a scientific concept is just that; it's a theory that tries to explain more about the world than previous theories have done. It is open to being challenged and to being proven incorrect.

There's no such thing as 'facts of life'. Only standing theories that haven't been disproved as of yet.

One thus sees that a new kind of theory is needed which drops these basic commitments and at most recovers some essential features of the older theories as abstract forms derived from a deeper reality in which what prevails in unbroken wholeness.