Origen's Commentary on the Gospel of Matthew: Book XIII. 11The Freedom of Sons.

11. The Freedom of Sons.

And this may be put in another way. There are some who are kings' sons on the earth, and yet they are not sons of those kings, but sons, and sons absolutely; but others, because of their being strangers to the sons of the kings of the earth, and sons of no one of those upon the earth, but on this very account are sons, whether of God or of His Son, or of some one of those who are God's. If, then, the Saviour inquires of Peter, saying, "The kings of the earth from whom do they receive toll or tribute--from their own sons or from strangers?" and Peter replies not from their own sons, but "from strangers," then Jesus says about such as are strangers to the kings of the earth, and on account of being free are sons, "Therefore the sons are free;" for the sons of the kings of the earth are not free, since "every one that committeth sin is the bond-servant of sin," but they are free who abide in the truth of the word of God, and on this account, know the truth, that they also may become free from sin. If, any one then, is a son simply, and not in this matter wholly a son of the kings of the earth, he is free. And nevertheless, though he is free, he takes care not to offend even the kings of the earth, and their sons, and those who receive the half-shekel; wherefore He says, "Let us not cause them to stumble, but go thou and cast thy net, and take up the fish that first cometh up," etc. But I would inquire of those who are pleased to make myths about different natures, of what sort of nature they were, whether the kings of the earth, or their sons, or those who receive the half-shekel, whom the Saviour does not wish to offend; it appears of a verity, ex hypothesi, that they are not of a nature worthy of praise, and yet He took heed not to cause them to stumble, and He prevents any stumbling-block being put in their way, that they may not sin more grievously, and that with a view to their being saved--if they will--even by receiving Him who has spared them from being caused to stumble. And as in a place verily of consolation,--for such is, by interpretation, Capernaum,--comforting the disciple as being both free and a son, He gives to him the power of catching the fish first, that when it came up Peter might be comforted by its coming up and being caught, and by the stater being taken from its mouth, in order to be paid to those whose the stater was, and who demanded as their own such a piece of money.