The punishment of absolute exile was not prescribed by the Law: because God was worshipped by that people alone, whereas all other nations were given to idolatry: wherefore if any man were exiled from that people absolutely, he would be in danger of falling into idolatry. For this reason it is related (1 Kings 26:19) that David said to Saul: “They are cursed in the sight of the Lord, who have cast me out this day, that I should not dwell in the inheritance of the Lord, saying: Go, serve strange gods.” There was, however, a restricted sort of exile: for it is written in Deut. 19:4 [Cf. Num. 35:25] that “he that striketh [Vulg.: ‘killeth’] his neighbor ignorantly, and is proved to have had no hatred against him, shall flee to one of the cities” of refuge and “abide there until the death of the high-priest.” For then it became lawful for him to return home, because when the whole people thus suffered a loss they forgot their private quarrels, so that the next of kin of the slain were not so eager to kill the slayer.
Reply Obj. 11: Dumb animals were ordered to be slain, not on account of any fault of theirs; but as a punishment to their owners, who had not safeguarded their beasts from these offenses. Hence the owner was more severely punished if his ox had butted anyone “yesterday or the day before” (in which case steps might have been taken to avoid the danger) than if it had taken to butting suddenly.—Or again, the animal was slain in detestation of the sin; and lest men should be horrified at the sight thereof.
Reply Obj. 12: The literal reason for this commandment, as Rabbi Moses declares (Doct. Perplex. iii), was because the slayer was frequently from the nearest city: wherefore the slaying of the calf was a means of investigating the hidden murder. This was brought about in three ways. In the first place the elders of the city swore that they had taken every measure for safeguarding the roads. Secondly, the owner of the heifer was indemnified for the slaying of his beast, and if the murder was previously discovered, the beast was not slain. Thirdly, the place, where the heifer was slain, remained uncultivated. Wherefore, in order to avoid this twofold loss, the men of the city would readily make known the murderer, if they knew who he was: and it would seldom happen but that some word or sign would escape about the matter. Or again, this was done in order to frighten people, in detestation of murder. Because the slaying of a heifer, which is a useful animal and full of strength, especially before it has been put under the yoke, signified that whoever committed murder, however useful and strong he might be, was to forfeit his life; and that, by a cruel death, which was implied by the striking off of its head; and that the murderer, as vile and abject, was to be cut off from the fellowship of men, which was betokened by the fact that the heifer after being slain was left to rot in a rough and uncultivated place.