Albert Barnes on 1 Corinthians 12:15

If the foot shall say, etc. The same figure and illustration which Paul here uses occurs also in heathen writers. It occurs in the apologue which was used by Menenius Agrippa, as related by Livy, (lib. ii. cap. 32,) in which he attempted to repress a rebellion which had been excited against the nobles and senators, as useless and cumbersome to the state. Menenius, in order to show the folly of this, represents the different members of the body as conspiring against the stomach, as being inactive, and as refusing to labour, and consuming everything. The consequence of the conspiracy which the feet, and hands, and mouth entered into, was a universal wasting away of the whole frame, for want of the nutriment which would have been supplied from the stomach. Thus he argued it would be by the conspiracy against the nobles, as being inactive, and as consuming all things. The representation had the desired effect, and quelled the rebellion. The same figure is used also by AEsop. The idea here is, that as the foot and the ear could not pretend that they were not parts of the body, and even not important, because they were not the eye, etc., that is, were not more honourable parts of the body, so no Christian, however humble his endowments, could pretend that he was useless because he was not more highly gifted, and did not occupy a more elevated rank.