Walnut and human brain

“Windfall fruits are ideally packaged so that they do not get ­damaged when they hit the ground. The way a walnut is packaged is the same as for a man’s brain: (a) core/brain, (b) soft core skin/meninges, (c) hard core skin/meninges with vertical and horizontal walls, (d) hard shell/bone layer, (e) fruit husk/skin layer.”

1939, © Fritz Kahn