Philo Judaeus Quod Deterius Potiori Insidiari Soleat 43

[43] For, as in medical science, some practitioners who know how to cure almost every complaint, and disease, and infirmity, can nevertheless give no true or even probable account of any one of them; and on the other hand, others are very clever, as far as giving an account of the diseases goes, and in explaining their symptoms and causes, and the modes of cure, and are the most excellent interpreters possible of the principles of which their art is made up, but are utterly useless in the matter of attending the bodies of the sick, to the cure of which they are not able to contribute even the slightest assistance. In the same way, those who have devoted themselves to practical wisdom have often neglected to pay attention to their language; and those who have learnt their professions thoroughly as far as words go, have yet treasured up no good instruction in their soul.