1 Corinthians 12:17-19

If the whole body were an eye, where would the hearing be? If the whole [body] were an ear, where would the sense of smell be? But now [as things really are], God has placed and arranged the parts in the body, each one of them, just as He willed and saw fit [with the best balance of function]. If they all were a single organ, where would [the rest of] the body be?