Hippocrates: Doing

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

Hippocrates

Epidemics, Book I, Ch. 2, Full text online at Wikisource
Variant translation: 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.
Paraphrased variants:
Wherever a doctor cannot do good, he must be kept from doing harm.
Viking Book of Aphorisms : A Personal Selection (1988) by W. H. Auden and Louis Kronenberger, p. 213.

Disease , Help

“Conclusions which are merely verbal cannot bear fruit, only those do which are based on demonstrated fact.”

Hippocrates

Precepts, Ch. 2, as translated by W. H. S. Jones (1923).
Context: Conclusions which are merely verbal cannot bear fruit, only those do which are based on demonstrated fact. For affirmation and talk are deceptive and treacherous. Wherefore one must hold fast to facts in generalizations also, and occupy oneself with facts persistently, if one is to acquire that ready and infallible habit which we call "the art of medicine."

“I would give great praise to the physician whose mistakes are small, for perfect accuracy is seldom to be seen, since many physicians seem to me to be in the same plight as bad pilots, who, if they commit mistakes while conducting the ship in a calm do not expose themselves, but when a storm and violent hurricane overtake them, they then, from their ignorance and mistakes, are discovered to be what they are, by all men, namely, in losing their ship.”

Hippocrates

p, 125
Ancient Medicine

Men , Perfection

“Those diseases which medicines do not cure, iron cures; those which iron cannot cure, fire cures; and those which fire cannot cure, are to be reckoned wholly incurable.”

Hippocrates

7:87
Variant translation: What cannot be cured by medicaments is cured by the knife, what the knife cannot cure is cured with the searing iron, and whatever this cannot cure must be considered incurable.
Aphorisms

Disease

“Life is short, and Art long; the crisis fleeting; experience perilous, and decision difficult. The physician must not only be prepared to do what is right himself, but also to make the patient, the attendants, and externals cooperate.”

Hippocrates

Ὁ βίος βραχὺς, ἡ δὲ τέχνη μακρὴ, ὁ δὲ καιρὸς ὀξὺς, ἡ δὲ πεῖρα σφαλερὴ, ἡ δὲ κρίσις χαλεπή. Δεῖ δὲ οὐ μόνον ἑωυτὸν παρέχειν τὰ δέοντα ποιεῦντα, ἀλλὰ καὶ τὸν νοσέοντα, καὶ τοὺς παρεόντας, καὶ τὰ ἔξωθεν.
1:1, Variant translation: Art is long; life is short; opportunity is fleeting; judgement is difficult; experience is deceitful. Compare: "The lyfe so short, the craft so long to lerne", Geoffrey Chaucer, The Assembly of Fowles, line 1.
Aphorisms

Life , Art , Decision

“To do nothing is sometimes a good remedy.”

Hippocrates

As quoted in A New Dictionary of Quotations on Historical Principles from Ancient and Modern Sources (1942) by H. L. Mencken