John Calvin Commentary 1 Corinthians 12:20

"But now they are many members, but one body." — 1 Corinthians 12:20 (ASV)

Many members — one body. He repeats this more often because the emphasis of the whole question lies here — that the unity of the body is of such a nature that it can only be maintained by a diversity of members; and that while the members differ from each other in offices and functions, they do so in such a way as to have a mutual connection with each other for the preservation of the one body. Therefore, no body can retain its standing without a diversified symmetry of its members, so that we may learn to promote both public and private advantage, by each one discharging the duty of their own station.