3 What then is their consolation for all these things? The power of Him that sends them. Wherefore also He puts this before all, saying, “Behold, I send you.” This suffices for your encouragement, this for confidence, and fearing none of your assailants.
Do you see authority? Do you see prerogative? Do you see invincible might? Now His meaning is like this: “Be not troubled” (so He speaks), “that sending you among wolves, I command you to be like sheep and like doves. For I might indeed have done the contrary, and have suffered you to undergo nothing terrible, nor as sheep to be exposed to wolves; I might have rendered you more formidable than lions; but it is expedient that so it should be. This makes you also more glorious; this proclaims also my power.”
This He said also unto Paul: “My grace is sufficient for you, for my strength is made perfect in weakness.” “It is I, now mark it, who have caused you so to be.” For in saying, “I send you forth as sheep,” He intimates this. “Do not therefore despond, for I know, I know certainly, that in this way more than any other ye will be invincible to all.”
After this, that they may contribute something on their own part also, and that all might not seem to be of His grace, nor they supposed to be crowned at random, and vainly, He says, “Be therefore wise as serpents, and harmless as doves.” “But what,” it might be said, “will our wisdom avail in so great dangers? Nay, how shall we be able to have wisdom at all, when so many waves are drenching us all over? For let a sheep be ever so wise, when it is in the midst of wolves, and so many wolves, what will it be able to do? Let the dove be ever so harmless, what will it profit, when so many hawks are assailing it?” In the brutes indeed, not at all: but in you as much as possible.
But let us see what manner of wisdom He here requires. That of the serpent, He says. For even as that animal gives up everything, and if its very body must be cut off, does not very earnestly defend it, so that it may save its head; in like manner do thou also, says He, give up every thing but the faith; though goods, body, life itself, must be yielded. For that is the head and the root; and if that be preserved, though thou lose all, you will recover all with so much the more splendor.
On this account then He neither commanded to be merely a simple and single-hearted sort of person, nor merely wise; but has mixed up both these, so that they may become virtue; taking in the wisdom of the serpent that we may not be wounded in our vitals; and the harmlessness of the dove, that we may not retaliate on our wrongdoers, nor avenge ourselves on them that lay snares; since wisdom again is useless, except this be added. Now what, I ask, could be more strict than these injunctions? Why, was it not enough to suffer wrong? Nay, says He, but I do not permit you so much as to be indignant. For this is “the dove.” As though one should cast a reed into fire, and command it not to be burnt by the fire, but to quench it.
However, let us not be troubled; nay, for these things have come to pass, and have had an accomplishment, and have been shown in very deed, and men became wise as serpents, and harmless as doves; not being of another nature, but of the same with us.
Let not then any one account His injunctions impracticable. For He beyond all others knows the nature of things; He knows that fierceness is not quenched by fierceness, but by gentleness. And if in men's actual deeds too you would see this result, read the book of the Acts of the Apostles, and you will see how often, when the people of the Jews had risen up against them and were sharpening their teeth, these men, imitating the dove, and answering with suitable meekness, did away with their wrath, quenched their madness, broke their impetuosity. As when they said, “Did not we strictly command you, that you should not speak in this name?” although able to work any number of miracles, they neither said nor did anything harsh, but answered for themselves with all meekness, saying, “Whether it be right to hearken unto you more than unto God, judge ye.”
Have you seen the harmlessness of the dove? Behold the wisdom of the serpent. “For we cannot but speak the things, which we know and have heard.” Do you see how we must be perfect on all points, so as neither to be abased by dangers, nor provoked by anger?
Source: Homilies on the Gospel of St. Matthew (New Advent)