[37] And if any one beholding some persons who may have been bought and sold by traffickers in men, looks upon them at once as slaves, he is widely removed from the truth; for an act of selling does not make him who purchases the master, nor him who is sold the slave, since fathers at times have paid a price for their sons, and sons have often laid down a ransom for their fathers, in cases where they have been carried away as prisoners by some piratical sally, or have been taken captive in regular warfare, though still the laws of nature, which are more stable than those of men, describe them as free.