Galen's Commentaries on the Aphorisms of Hippocrates

[reaso]n. For none of us may suffice both to establish and to complete the art at the same time, but it ought to seem sufficient if, receiving what predecessors have discovered over the span of many years and adding something to them, their successors might at some time complete and perfect it. For either on account of one of these things, or on account of both, it seems to me that he used such a proem, as if he had written thus: Since the magnitude of the art exceeds the life of man, so much so that it cannot be both begun and brought to its end by a man, however diligent and hardworking, therefore it is worth the effort for each to commit to letters those things which he has learned, and to hand down to posterity commentaries which may diligently and quickly govern the whole nature of things to be taught, and interpret them in clear speech. That the art is indeed long, these words which follow show: “Opportunity is fleeting, experiment perilous, and judgment difficult.” As if he had said: “Life is short, but the art is long, because opportunity is fleeting, experiment is perilous, and judgment is difficult.” For on account of this is the art long: because the opportunity for doing things in it is extremely fleeting—that is, very narrow and almost momentary. And furthermore, since there are two instruments through which remedies are found, namely reason and experience, the latter indeed is perilous, while reason is difficult—that is, it is not easy to know which is the truer. Moreover, it is not difficult to show in a few words that what they say is true. For opportunity is fleeting on account of the flux of matter—I mean the body—which flows continuously and is transformed in a moment of time. Experiment, too, is itself perilous by reason of the matter; for bricks, clay, wood, stones, tiles, and hides are not the matter of the medicinal art as they are of others, in which it is permitted to experiment in many ways with impunity, and to practice upon the matter, and to be engaged in every contemplation of theorems. As carpenters do with wood, or tanners with hides; for if you destroy wood or hide by handling them badly, no danger follows therefrom. But to experiment upon the human body with those things which have not been proven by experience is not without danger, since a bad experiment ends in the death of the whole animal. And indeed judgment (moreover, reason itself is judgment, since they judge by those things which are to be done) is difficult, and true judgment or true reason is not easily found, which the multitude of sects in the medicinal art demonstrates. For if truth were easy to find, so many and such great men who sought it would never have been divided into such contrary sects. To the Empiricists, however, reason does not seem to be called judgment, but rather the discrimination of those aids which were discovered through experience. For to confess the truth, even this is difficult and not easy to explore, when many remedies have been applied to a sick person and one of them is said to have been the cause of the patient either being better or worse; if he should happen to have slept, then been anointed, and afterwards applied a plaster, then a clyster, or had a spontaneous evacuation of the bowels, and then eaten, and consumed such foods, and after all these things felt relief or harm, it is not easy to say which of those things done to him either helped or hindered. For all these reasons, therefore, judgment is very difficult. Now let us gather the whole discourse into one heading: The art indeed becomes long if we measure it by the life of one man. It is expedient, moreover, to leave commentaries to posterity, especially those that are compendious and aphoristic. For such a mode of teaching is most useful both for primary instruction and for retaining in memory those things which we have learned, or, if by chance forgetfulness should intervene, for recalling them to memory. The following words also harmonize with these; for as one who has made a proem to a commentary, and appropriately subjoining those things which were to be written in it, he uttered these words: “It is necessary not only to exhibit oneself doing the opportune things, but also the patient, the attendants, and external circumstances.” If anyone, he says, is at any time to judge those things which are written in this book