It is in itself a rather successful theory, leading to definite conclusions.

Relativity, beginning with Einstein, is physicists' most successful theory for understanding space and time.

(C) For any successful theory, the account must not be circular.

Any new physical theory is supposed to reduce to successful old theories in some approximation.

The relativity/dark matter combination, however, is just the most successful theory of gravity; it's not the only one.

Natural selection is a successful theory devised to explain the fact of evolution.

A successful unified theory must therefore necessarily incorporate this principle.

No really successful physical theory ever completely disappears from the scene.

No similarly successful theory has been developed for knots in general.

Despite this, evolution is one of the most successful theories in science.