Time is that wherein there is opportunity, and opportunity is that wherein there is no great time. Healing is a matter of time, but it is sometimes also a matter of opportunity. However, knowing this, one must attend to medical practice not primarily to plausible theories, but to experience combined with reason. For a theory is a composite memory of things apprehended with sense perception.

Precepts, Ch. 1, as translated by W. H. S. Jones (1923).