On the Making of Silk Purses From Sows' Ears - A Contribution to Philosophy #228114

When the time comes for it to make the Great Change, to transform itself from a gluttonous worm into a winged moth, to cease its gross existence as a creeping thing and to enter into an aerial life, to sip honey and to make love, it requires an envelope for hiding, for a dark and secret place, according to the command of Nature. From certain glands at the back of its head it ejects two minute threads of a viscous liquid which become coated with another secretion flowing from two other convenient glands, and these two little streams are thus cemented to a double strand.