The classical writers felt rightly that the Celtic idea of immortality was something altogether different from this. It was both loftier and more realistic; it implied a true persistence of the living man, as he was at present, in all his human relations. They noted with surprise that the Celt would lend money on a promissory note for repayment in the next world.(60) That is an absolutely Egyptian conception. And this very analogy occurred to Diodorus in writing of the Celtic idea of immortality—it was like nothing that he knew of out of Egypt.(61) *The Doctrine of Transmigration* Many ancient writers assert that the Celtic idea of immortality embodied the Oriental conception of the transmigration of souls, and to account for this the hypothesis was invented that they had learned the doctrine from Pythagoras, who represented it in classical antiquity. Thus Cæsar: “The principal point of their [the Druids’] teaching is that the soul does not perish, and that after death it passes from one body into another.” And Diodorus: “Among them the doctrine of Pythagoras prevails, according to which the souls of men are immortal, and after a fixed term recommence to live, taking upon themselves a new body.” Now traces of this doctrine certainly do appear in Irish legend. Thus the Irish chieftain, Mongan, who is an historical personage, and whose death is recorded about A.D. 625, is said to have made a wager as to the place of death of a king named Fothad, slain in a battle with the mythical hero Finn mac Cumhal in the third century. He proves his case by summoning to his aid a _revenant_ from the Other-world, Keelta, who was the actual slayer of Fothad, and who describes correctly where the tomb is to be found and what were its contents. He begins his tale by saying to Mongan, “We were with thee,” and then, turning to the assembly, he continues: “We were with Finn, coming from Alba....” “Hush,” says Mongan, “it is wrong of thee to reveal a secret.” The secret is, of course, that Mongan was a reincarnation of Finn.(62) But the evidence on the whole shows that the Celts did not hold this doctrine at all in the same way as Pythagoras and the Orientals did. Transmigration was not, with them, part of the order of things. It _might_ happen, but in general it did not; the new body assumed by the dead clothed them in another, not in this world, and so far as we can learn from any ancient authority, there does not appear to have been any idea of moral retribution connected with this form of the future life. It was not so much an article of faith as an idea which haunted the imagination, and which, as Mongan’s caution indicates, ought not to be brought into clear light.