1 Corinthians 12:18-21

But God has carefully designed each member and placed it in the body to function as he desires. A diversity is required, for if the body consisted of one single part, there wouldn’t be a body at all! So now we see that there are many differing parts and functions, but one body. It would be wrong for the eye to say to the hand, “I don’t need you,” and equally wrong if the head said to the foot, “I don’t need you.”