First dentistry was painless; then bicycles were chainless; and now, it seems, they're making progress in a matter that even I thought hopeless—namely, making love-making brainless.

A humorous, satirical observation that lists modern “improvements” and ends by joking that romance is being reduced to something requiring less thought.

The speaker mocks the idea of technological or social progress by suggesting that some changes make life easier but also encourage shallowness, culminating in a joke about intimacy becoming mindless.