in the world of men.  Before the problem of foreign gods had begun to exist for the Romans, in the good old days when they knew only the gods of their own religion, the pomerium served to keep within the bounds of Rome all the beneficent kindly gods whose presence was not needed outside in the fields, and it served fully as important a purpose in keeping outside of Rome the gods who were feared rather than loved, for example the dread war-god Mars.  When foreign gods began to be introduced into Rome they might, of course, be worshipped inside the pomerium by private individuals, but when the state acknowledged them it was more prudent that her worship should be outside the sacred wall.  Thus it came to pass that the foreign gods, who were taken into the cult of the Roman state, were given temples in the Campus Martius or over on the Aventine, and the two or three cases where they were publicly worshipped inside the pomerium form no real exception to this rule—­such an exception would be, in fact, quite unthinkable in the strictly logical system of Roman worship—­but these gods were allowed inside because they came to Rome from her kinsfolk, the Latins, and were not felt to be foreign.

Hercules is one of the cases in this last category.  Though originally, as we have seen, a Greek god, his long residence in Tibur (Tivoli) had made him, as it were, a naturalised citizen of Latium, and hence Rome felt it no impropriety to take him inside her pomerium.  At first his worship seems to have been carried on by two clans, the Potitii and the Pinarii, but later, during the republic, the state assumed control.  But though it was really the Greek Herakles who had come in as the latinised Hercules, the god had paid a certain price for his admission, for he came stripped of all the various attributes which he had had in Greece and retaining merely his function as patron of trade and travel.  It was this practical side of his nature alone which appealed to the Romans; it found its expression in the offering of “the tenth” at the great altar in the Forum Boarium.  This altar always remained in a certain sense the centre of Hercules-worship in Rome.  It was reinforced at an early date by no less than three temples of Hercules in the more or less immediate neighbourhood, all of which were characterised by the same relative simplicity of ritual.  Centuries later Herakles became known to the Romans through direct Greek channels, and it was recognised that this new Herakles was akin to the old Hercules, so that he too was called Hercules.  There was nothing surprising in this to the Romans, because they considered it a matter of course that there should be found a parallel among their own gods for each Greek deity.  They never understood the true state of affairs; it is doubtful whether they could have understood it:  namely, that in almost all their other identifications of Roman and Greek deities, they were really doing violence to their own native gods by superimposing