Woolvard summarized well, “This verse forms an excellent three-part summary of the rest of the chapter. (a) The human body is a unit (cf. v. 13 on the unity of the body of Christ). (b) The human body has many parts, with a necessary diversity in its members (cf. vv. 14-20). (c) The parts of the human body work together as one, with a dependent mutuality as each part fulfills an important function (cf. vv. 21-26). Likewise the body of Christ has a diversity of parts functioning together (vv. 27-30).”