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