Page:The Harveian oration 1866.djvu/22

 and yet science has not yet thoroughly explained the actions of these two instruments.

Our purely scientific knowledge in physiology and pathology keeps us from falling into errors; it saves us from being "carried about by every wind of doctrine;" it is often a trustworthy guide in the prevention of disease, and not unfrequently in its treatment; it may, possibly, at some distant day, become the sole basis of medicine, and may enable physicians to select their remedies for disease by simple deduction from established laws; but, until that happy time arrive, we must be content, and only too glad, to make use of all the powers that nature has revealed to us, whether we have, or have not, a clear view as to their modes of operation.

Practical medicine, as I have already said, has had modes of progress of its own. The independent study of disease has often led to real knowledge in advance of physiology. In some cases the method has been inductive, the results of a large experience being generalised into principles and methodised into rules for practice. The work done by Sydenham is an illustration:—the more apt,