And that wild thought of metempsychôsis was connected with a theory, yet more fantastic, of the visible heaven above us. For Pythagoras, the Pythagoreans, had had their views also, as became the possessors of "a first principle"--of a philosophy therefore which need leave no problem untouched--on purely material things, above all on the structure of the planets, the mechanical contrivances by which their motion was effected (it came to just that!) on the relation of the earth to its atmosphere and the like. The doctrine of the transmigration, [69] the pilgrimage or mental journeys, of the soul linked itself readily with a fanciful, guess-work astronomy, which provided starry places, wide areas, hostelries, for that wanderer to move or rest in. A matter of very lively and presentable form and colour, as if making the invisible show through, this too pleased the extremely visual fancy of Plato; as we may see, in many places of the Phaedo, the Phaedrus, the Timaeus, and most conspicuously in the tenth book of The Republic, where he relates the vision of Er--what he saw of the other world during a kind of temporary death. Hell, Purgatory, Paradise, are briefly depicted in it; Paradise especially with a quite Dantesque sensibility to coloured light--physical light or spiritual, you can hardly tell which, so perfectly is the inward sense blent with its visible counter-part, reminding one forcibly of the Divine Comedy, of which those closing pages of The Republic suggest an early outline. That then is the third element in Plato derivative from his Pythagorean masters: an astronomy of infant minds, we might call it, in which the celestial world is the scene, not as yet of those abstract reasonable laws of number and motion and space, upon which, as Plato himself protests in the seventh book of The Republic, it is the business of a veritable science of the stars to exercise our minds, but rather of a machinery, which the mere star-gazer may peep into as best he can, with its levers, its spindles and revolving [70] wheels, its spheres, he says,--"like those boxes which fit into one another," and the literal doors "opened in heaven," through which, at the due point of ascension, the revolving pilgrim soul will glide forth and have a chance of gazing into the wide spaces beyond, "as he stands outside on the back of the sky"--that hollow partly transparent sphere which surrounds and closes in our terrestrial atmosphere. Most difficult to follow in detailed description, perhaps not to be taken quite seriously, one thing at least is clear about the planetary movements as Plato and his Pythagorean teachers conceive them. They produce, naturally enough, sounds, that famous "music of the spheres," which the undisciplined ear fails to recognise, to delight in, only because it is never silent.