There are in fact two things, science and opinion; the former begets knowledge, the latter ignorance.

As to diseases, make a habit of two things — to help, or at least, to do no harm.

The physician must be able to tell the antecedents, know the present, and foretell the future — must mediate these things, and have two special objects in view with regard to disease, namely, to do good or to do no harm.

In whatever disease sleep is laborious, it is a deadly symptom; but if sleep does good, it is not deadly.

What medicines do not heal, the lance will; what the lance does not heal, fire will.

I have clearly recorded this: for one can learn good lessons also from what has been tried but clearly has not succeeded, when it is clear why it has not succeeded.

And if this were so in all cases, the principle would be established, that sometimes conditions can be treated by things opposite to those from which they arose, and sometimes by things like to those from which they arose.

Correct is to recognize what diseases are and whence they come; which are long and which are short; which are mortal and which are not; which are in the process of changing into others; which are increasing and which are diminishing; which are major and which are minor; to treat the diseases that can be treated, but to recognize the ones that cannot be, and to know why they cannot be; by treating patients with the former, to give them the benefit of treatment as far as it is possible.