John Chrysostom
The Apostle explains this later, but now he turns to the members themselves and says: "If the foot should say, 'Because I am not a hand, I am not of the body,' is it therefore not of the body? And if the ear should say, 'Because I am not an eye, I am not of the body,' is it therefore not of the body?" (1 Cor 12:15-16). If the fact that one is lesser and another greater prevented them from entering into the body's composition, then the whole body would not exist. Therefore do not say, "I am not a body because I am less than others." The foot occupies the lower place, yet it too is part of the body. Whether one is or is not part of the body does not depend on being placed here or there. That makes only a difference of place. It depends on union or division.
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To be or not to be a body depends on being joined to it or not joined to it. Notice Paul's wisdom in presenting your members as speaking these words. As above he said, "I have applied these things to myself and Apollos" (1 Cor 4:6), so here, to make his speech still gentler and easier to receive, he presents the members themselves as speaking. Thus the readers, hearing an answer to themselves from nature itself, and being reproved by experience itself and by common sense, could no longer contradict. Even if you say the same thing, he says, and however much you object, you cannot be outside the body. For both the law of nature, and still more the power of grace, preserves and keeps all things. See how he avoids excess. He does not speak of all the members, but only of two, and those at the extremes: the highest, the eye, and the lowest, the feet. Moreover, he presents the foot as speaking not with the eye, but with the hand, which is a little higher than it, and the ear with the eye. As we usually envy not those who greatly surpass us, but those who are only a little above us, so he makes his comparison.