1 Corinthians 12:14-18, 21-22

For the body is not one member, but many. If the foot says, “Because I am not a hand, I am not a part of the body,” it is not for this reason any the less a part of the body. And if the ear says, “Because I am not an eye, I am not a part of the body,” it is not for this reason any the less a part of the body. If the whole body were an eye, where would the hearing be? If the whole were hearing, where would the sense of smell be? But now God has placed the members, each one of them, in the body, just as He desired.

And the eye cannot say to the hand, “I have no need of you”; or again the head to the feet, “I have no need of you.” On the contrary, it is much truer that the members of the body which seem to be weaker are necessary