1 Corinthians 12:14-19

For the [human] body does not consist of one part, but of many [limbs and organs]. If the foot says, “Because I am not a hand, I am not a part of the body,” is it not on the contrary still a part of the body? If the ear says, “Because I am not an eye, I am not a part of the body,” is it not on the contrary still a part of the body? 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?