Read it through once

[Footnote III.19: _No traveller returns_,] The traveller whom Hamlet had seen, though he appeared in the same habit which he had worn in his life-time, was nothing but a shadow, "invulnerable as the air," and, consequently, _incorporeal_. The Ghost has given us no account of the region from whence he came, being, as he himself informed us, "forbid to tell the secrets of his prison-house."--MALONE.]