Upon this answer Sokrates proceeds to cross-examine: _Sokr._--Do you think that good men are useful, bad men useless? _Erast._--Yes I do. _Sokr._--You think that philosophers, as you describe them, are useful? _Erast._--Certainly: extremely useful. _Sokr._--But tell me on what occasions such second-best men are useful: for obviously they are inferior to each separate artist. If you fall sick will you send for one of _them_, or for a professional physician? _Erast._--I should send for both. _Sokr._--That is no answer: I wish to know, which of the two you will send for first and by preference? _Erast._--No doubt I shall send for the professional physician. _Sokr._--The like also, if you are in danger on shipboard, you will entrust your life to the pilot rather than to the philosopher: and so as to all other matters, as long as a professional man is to be found, the philosopher is of no use? _Erast._--So it appears. _Sokr._--Our philosopher then is one of the useless persons: for we assuredly have professional men at hand. Now we agreed before, that good men were useful, bad men useless.[15] _Erast._--Yes; that was agreed. [Footnote 15: Plat. Erast. 136 C-D.] [Side-note: Philosophy cannot consist in multiplication of learned acquirements.] _Sokr._--If then you have correctly defined a philosopher to be one who has a second-rate knowledge on many subjects, he is useless so long as there exist professional artists on each subject. Your definition cannot therefore be correct. Philosophy must be something quite apart from this multifarious and busy meddling with different professional subjects, or this multiplication of learned acquirements. Indeed I fancied, that to be absorbed in professional subjects and in variety of studies, was vulgar and discreditable rather than otherwise.[16] [Footnote 16: Plato, Erast. 137 B.] Let us now, however (continues Sokrates), take up the matter in another way. In regard to horses and dogs, those who punish rightly are also those who know how to make them better, and to discriminate with most exactness the good from the bad? _Erast._--Yes: such is the fact. [Side-note: Sokrates changes his course of examination--questions put to show that there is one special art, regal and political, of administering and discriminating the bad from the good.]