"'Heaven above knows. You can say whatever you like. It might be anything.' "'Would it account for actual morphological changes of tissue?' I asked. "'I wouldn't say it wouldn't; that would depend on the changes; but I should be very pleased to look through those portions of your proofs, Mr Rose,' he said.... "So that was that. I went straight off to Cambridge Circus to get the Blair-Bell book, but, as I say, I saw you across the road, so I got the book somewhere else." "The pineal gland!" I murmured, dazed. "Yes. One name for it's The Third Eye. Don't ask me to explain it. But if I understand my doctor-man the idea's something like this: There are these degenerated organs that man in his present stage of development has outgrown. A lizard's got what they call The Third Eye, and so has a lamprey, and lots of creatures. And the whole thing's the wildest nightmare imaginable. Takes you right back to fecund mud and the first seminal atom. One fellow, I forget his name, has a most hair-raising theory. He says that what they call the 'ancestral type' lived in the sea, rolling about like a log I suppose--anyway it doesn't seem to have mattered whether he was upside-down or not. So its back and front were both alike. But as time went on it was more often one way up than another, and the creature began to adapt itself. It grew new eyes where it found them most convenient and stopped using the old one. Very likely the old one's the pineal gland. Or words to that effect.... So if you're now a 'bilaterally symmetrical animal with forward progression,' and your front's where you back used to be, and anything goes wrong, you're a sort of Mr Facing-Both-Ways, with two memories like me and all the rest of it.... And a whole philosophy's been built up on it. Roughly, a man's spirit and matter interpenetrate throughout every particle of him so that there's no dividing them--everywhere except in one place. There they exist independently and side by side. All the mystery of life and death's supposed to be located there. And that place is the pineal gland."