„It would be better, I think, for the man who really seeks the truth not to ask what the poets say; rather, he should first learn the method of finding the scientific premises that I discussed in the second book; then he should train and exercise himself in this method; and when his training is sufficiently advanced, then, as he approaches each particular problem, he should enquire into the premise needed for proving it, which premise he should take from simple sense-perception, which from experience, whether drawn from life or from the arts, which from the truths clearly apprehended by the mind, in order to draw out from them the desired conclusion.“
— Galén Roman physician, surgeon and philosopher 129 - 216
Galen, On the Doctrines of Hippocrates and Plato,: PHP III 8.35.1-11 translation: De Lacy, Phillip (1978- 1984) Galen, On the Doctrines of Hippocrates and Plato, Berlin. p. 233; cited in: Christopher Jon Elliott. "Galen, Rome and the Second Sophistic." p. 147-8.