“What is the good of a newborn baby?”
Benjamin Franklin (1706–1790) American author, printer, political theorist, politician, postmaster, scientist, inventor, civic activist, …
Widely attributed response to a questioner doubting the usefulness of hot air balloons. See Seymor L. Chapin, "A Legendary Bon Mot?: Franklin's 'What is the Good of a Newborn Baby?'", Proceedings of the American Philosophical Society, 129:3 (September 1985), pp. 278–290. Chapin argues (pp. 286–287) that the "evidence overwhelmingly suggests that he said something rather different" and that the attributed quotation is "a probably much older adage".
Attributed