XI. (52) This then is what appears to be said of these holy men; and it is indicative of a nature more remote from our knowledge than, and much superior to, that which exists in the objects of outward sense; for the sacred word appears thoroughly to investigate and to describe the different dispositions of the soul, being all of them good, the one aiming at what is good by means of instruction, the second by nature, the last by practice; for the first, who is named Abraham, is a symbol of that virtue which is derived from instruction; the intermediate Isaac is an emblem of natural virtue; the third, Jacob, of that virtue which is devoted to and derived from practice. (53) But we must not be ignorant that each of these men was endowed with all these powers, but that each derived his name from that one which predominated in him and mastered the others; for neither is it possible for instruction to be made perfect without natural endowments and practice, nor is nature able to arrive at the goal without instruction and practice, nor is practice unless it be founded on natural gifts and sound instruction. (54) Very appropriately, therefore, he has represented, as united by relationship, these three, which in name indeed are men, but in reality, as I have said before, virtues, nature, instruction, and practice, which men also call by another name, and entitle them the three graces (charites), either from the fact of God having bestowed (kecharisthai) on our race those three powers, in order to produce the perfection of life, or because they themselves have bestowed themselves on the rational soul as the most glorious of gifts, so that the eternal name, as set forth in the scriptures, may not be used in conjunction with three men, but rather with the aforesaid powers; (55) for the nature of mankind is mortal, but that of virtues is immortal; and it is more reasonable that the name of the everlasting God should be conjoined with what is immortal than with what is mortal, since what is immortal is akin to what is imperishable, but death is hostile to it.