XIII. (41) In this manner, then, it is useful to oppose those who are ostentatious about doctrines. For if we have been well exercised in various species of discourses, we shall no longer stumble through inexperience and want of acquaintance with the manoeuvres of sophists. But rising up and making a firm and resolute stand against them, we shall with ease escape from their artificial entanglements. But they, when their tricks have once been found out, will appear to be exhibiting the conduct of sparrers rather than of regular combatants. For they too, in their own opinion, get great credit by their style of beating the air; but when they come to a real contest they meet with no moderate disgrace. (42) And if any one is adorned as to his soul with all imaginable virtues, and yet has paid no attention to the art of speaking and arguing, if he only preserves silence he will obtain safety, a prize won without danger. But if he comes forth like Abel into a contest with sophists, he will be thrown down before he has obtained a firm footing. (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. (44) It is therefore nothing extraordinary, that these men being in the habit of indulging an unbridled tongue, should be full of self-sufficiency and boldness, displaying all the folly which they have from the first beginning cherished. But it is better to trust to those who, like skilful physicians, have a knowledge of the means of healing the diseases and evil affections of the soul, until God provides an excellent interpreter, and displays to and pours upon him the fountains of his eloquence.