72 And there are many other words which do not retain one uniform signification, but are introduced so as to suit a variety of connections, and thus are understood in a variety of ways, and sometimes, indeed, are adopted along with an explanation. We have an example in the saying, “Be not children in understanding; howbeit in malice be ye little children, that in understanding ye may be perfect.” For here is a sentence which, in a brief and pregnant form, might have been expressed thus: “Be not children; howbeit be ye children.”
The same is the case with the words, “If any man among you thinks himself to be wise in this world, let him become a fool that he may be wise.” For what else is the statement there but this: “Let him not be wise, that he may be wise”? Moreover, the sentences are sometimes so put as to exercise the judgment of the inquirer. An instance of this kind occurs in what is said in the Epistle to the Galatians: “Bear ye one another's burdens, and so you will fulfil the law of Christ. For if a man thinks himself to be something, when he is nothing, he deceives himself.
But it is meet that every man should prove his own work; and then shall he have rejoicing in himself, and not in another. For every man shall bear his own burden.” Now, unless the word “burden” can be taken in different senses, without doubt one would suppose that the same writer contradicts himself in what he says here, and that, too, when the words are placed in such close neighbourhood in one paragraph. For when he has just said, “One shall bear another's burdens,” after the lapse of a very brief interval he says, “Every man shall bear his own burden.”
But the one refers to the burdens which are to be borne in sharing in one's infirmity, the other to the burdens borne in the rendering of an account of our own actions to God: the former are burdens to be borne in our [duties of] fellowship with brethren; the latter are those peculiar to ourselves, and borne by every man for himself. And in the same way, once more, the “rod” of which the apostle spoke in the words, “Shall I come unto you with a rod?” is meant in a spiritual sense; while the same term bears the literal meaning when it occurs of the rod applied to a horse, or used for some other purpose of the kind, not to mention, in the meantime, also other metaphorical significations of this phrase.
Source: The Harmony of the Gospels (New Advent)