Numbers 18:8

He adds after these things: "And the Lord spoke to Aaron, saying: Behold, I have given to you, for keeping, the firstfruits." Although in some Latin copies it is written "for observing," yet it is more correct to read "for keeping." But it must be inquired how, according to the law, the firstfruits are kept. For the priests do not receive the firstfruits in order to keep them, but in order to consume them. How, then, does he say: "Behold, I have given to you the firstfruits for keeping"? Whence it is clear that this cannot be applied to the law of the letter, but to the law of the spirit. For those firstfruits which we expounded above spiritually can be kept; those others cannot. But also, if Christ is, according to the Apostle, firstfruits, truly these firstfruits have been given to us for keeping. For what is so blessed as that the soul which has received Christ should ever keep him and ever have him remaining in itself? And such a soul truly receives firstfruits for keeping. For those firstfruits which were offered in the law were consumed as food and, having entered into the belly, were digested, as the Gospel says, "into the draught." But whoever eats these firstfruits and tastes the bread "which came down from heaven, shall not die, but shall abide unto eternal life." For this is the bread which, though it be ever eaten, ever abides, nay rather ever increases. There is, therefore, as the Apostle also says, a "spiritual food" which, the more it is consumed, the more abundantly it grows. For the more you take of the word of God, the more earnestly you eat this food, the more plentifully will it abound in you. Let these things be said in regard to that which is written: "for keeping the firstfruits."

There follows: "of all the things that are sanctified to me by the sons of Israel." Neither is this said without a sacred meaning; for God does not will to receive firstfruits from anywhere except from the sanctified of Israel. For it might come to pass that even among the gentiles some works worthy of God should be found. For among them too some cultivated the virtues of the soul, and philosophy in some persons accomplished a little something; but he does not will these to be offered among the firstfruits. From those God wills to receive good deeds whose "mind sees God," and who have been sanctified to God through faith. But the gentile, even if he seem to have something honorable and praiseworthy in his morals, in this very thing that he does not ascribe the virtue of his soul to God but reckons it to his own boasting, such uprightness is not sanctified, and therefore it is not received among the firstfruits. But as far as pertains to the definition of the letter of the law, it seems also to exclude proselytes from a gift of this kind; for he wills only the sanctified of the sons of Israel to offer firstfruits. But I think that a man can be called an Israelite from the fact that it is permitted him to enter the church of God; for it is written: "You shall not abhor the Edomite, since he is your brother, nor the Egyptian, since you were a dweller in the land of Egypt. If sons be born to them, in the third generation they shall enter into the church of God." Until, therefore, the Egyptian or the Edomite bears fruit and has begotten sons of the first and second and third generation, he cannot enter into the church of the Lord; but the generation of sons makes them enter into the church of the Lord. Let him observe more diligently who reads the divine letters and does not, as he pleases, pass over the words of Scripture, but looks to each and every expression, how he did not say, "If sons or daughters be born to them," but, "If sons be born to them, in the third generation they shall enter into the church of the Lord." And consider, if you can, according to the mystical sense, why it is only sons, not also daughters, who cause the fathers to enter into the church of the Lord. Finally, you will find that even the saints, to whom an outstanding testimony is given by God, hardly begot daughters, but sons. Abraham did not beget daughters; Isaac neither did so…