The introduction of a new deity now and again was not of great account from the point of view of religion, except in so far as it encouraged the new ceremonies; the Romans had never taken much personal interest in their deities, and the arrival (outside the pomoerium in each case) of Hermes under the name of Mercurius, or Poseidon bearing the name of the old Roman water _numen_ Neptunus, or even of Asclepios with a Romanised name Aesculapius, would not be likely to affect greatly their ideas of the divine. These facts have rather a historical than a religious significance; Hermes Empolaios, for example, suggests trade with Greek cities, perhaps in grain,[544] and belongs therefore to the same class as Ceres, Liber, Libera, of whom I have already spoken. The arrival of Poseidon-Neptune may mean, as Dr. Carter has suggested, a kind of "marine insurance" for the vessels carrying the grain from Greek ports.[545] The settling of Aesculapius in the Tiber island in 293, as the result of a terrible pestilence, is interesting as being the first fact known to us in the history of medicine at Rome; the temple became a kind of hospital on the model of Epidaurus, where the god had been brought in the form of a snake by an embassy sent for the purpose, and the priests who served it were probably Greeks skilled in the healing art.[546] This last case is a curious example of new Roman religious experience, but it can hardly be said to have any deep significance in the religious history of Rome. Of the obliteration of the old _numen_ Neptunus by the Greek god who took his name we know nothing for good or ill; we are ignorant of the real meaning of the old _numen_, and cannot tell whether the loss of him was compensated by the usefulness of his name in Roman literature to represent the Greek god of the sea. Let us turn to the much more important subject of the new ceremonies ordered by the Sibylline "books." The first authentic case of such innovation occurred in 399 B.C., during the long and troublesome siege of the dangerous neighbour city Veii; I call it authentic because all the best modern authorities so reckon it, though it occurred before the destruction of old records during the capture of the city by the Gauls. The circumstances were such as to fix themselves in the memory of the people, and in one way or another they found their way into the earliest annals, probably those of Fabius Pictor, composed during the Second Punic War.[547]