The chapter opens
吾生也有涯，
而知也无涯 'our life has a limit, but knowledge has none', a warning against wearing out a finite life in chasing the infinite. At its centre is Cook Ding, who carves an ox for Lord Wenhui so smoothly that after nineteen years his knife is as sharp as new, because it only ever passes through the gaps between the joints. The lord says the cook's words have taught him how to nurture life, which is the chapter's subject:
养生 'nurturing life' plus
主 'the essential'.
