Lois McMaster Bujold Quote

"Most men", he quoted, "are of naught more use in their lives but as machines for turning food into shit."
Ivan cocked an eyebrow at him. "Who said that? Your grandfather?"
"Leonardo da Vinci," Miles returned primly. But was compelled to add, "Grandfather quoted it to me, though."

Vorkosigan Saga - Memory (1996)