XI. (77) We will now speak of his wife, Sarah, for she too had her name changed to Sarrah by the addition of the one element, the letter rho. These, then, are the names, and we must now explain what they mean. Sarah, being interpreted, signifies “my authority,” but Sarrah signifies “princess;” the former name, (78) therefore, is a symbol of specific virtue, but the latter of generic virtue. But in proportion as genus is superior to species in regard of quantity, in the same proportion does the latter name excel the former; for species is something small and perishable, but genus is numerous and immortal, (79) and the intention of God is to bestow great and immortal things instead of such as are small and perishable, and this is a task suited to his dignity. Now the prudence which exists in the virtuous man is the authority of himself alone, and he who has it would not err if he were to say, my authority is the prudence which is in me; but that which has stretched out this authority is generic prudence, not any longer the authority of this or that person, but absolute intrinsic authority; therefore that which exists only in species will perish at the same time with its possessor, but that which, like a seal, has stamped it with an impression, is free from all mortality, and will remain for ever and ever imperishable. (80) Thus also those arts which exist only in species perish along with those who have acquired them, such as geometricians, grammarians, and musicians, but the generic arts remain exempt from destruction. And, again, he gives an additional sketch of his meaning when he teaches by the same name that every virtue is a princess, and a queen, and a ruler of all the affairs of life.