touching the heart only; not, however, without medicinal law--as in the case of the other permission, "propter duritiem." But in this, more than in anything (though much in all, and though in this he would not himself allow of their application, for his own laws against usury are sharp enough), Plato's words are true in the fourth book of the "Polity," that neither drugs, nor charms, nor burnings, will touch a deep-lying political sore, any more than a deep bodily one; but only right and utter change of constitution; and that "they do but lose their labour who think that by any tricks of law they can get the better of these mischiefs of intercourse, and see not that they hew at a Hydra." [97] Hence Dante's companionship of Cahors, Inf., canto xi., supported by the view taken of the matter throughout the middle ages, in common with the Greeks. And indeed this Hydra seems so unslayable, and sin sticks so fast between the joinings of the stones of buying and selling, that "to trade" in things, or literally "cross-give" them, has warped itself, by the instinct of nations, into their worst word for fraud; for, because in trade there cannot but be trust, and it seems also that there cannot but also be injury in answer to it, what is merely fraud between enemies becomes treachery among friends: and "trader," "traditor," and "traitor" are but the same word. For which simplicity of language there is more reason than at first appears; for as in true commerce there is no "profit," so in true commerce there is no "sale." The idea of sale is that of an interchange between enemies respectively endeavouring to get the better of one another; but commerce is an exchange between friends; and there is no desire but that it should be just, any more than there would be between members of the same family. The moment there is a bargain over the pottage, the family relation is dissolved;--typically "the days of mourning for my father are at hand." Whereupon follows the resolve "then will I slay my brother."