For he was yet in the loins of his father - Abraham is here called the father of Levi, by a common use of the word, referring to a more remote ancestor than the literal father. The meaning of the apostle is, that he was even then, in a certain sense, in the loins of Abraham, when Melchizedek met him; or it was all the same as if he were there, and had then an existence. The relation which subsisted between him and Abraham, in the circumstances of the case, implied the same thing as if he had then been born, and had acted for himself by paying tithes. Instances of this occur constantly. A father sells a farm, to which his son would he heir, and it is the same as if the son had sold it. He has no more control over it than if he had been present and disposed of it himself. A father acknowledges fealty to a government for a certain title or property which is to descend to his heirs, and it is all one as if the heir had himself done it; and it is not improper to say that it is the same as if he had been there and acted for himself.
For some valuable remarks on the nature of the reasoning here employed, see Stuart on the Hebrews; Excursus xiv. The reasoning here is, indeed, especially such as would be suited to impress a Jewish mind, and perhaps more forcibly than it does ours. The Jews valued themselves on the dignity and honor of the Levitical priesthood, and it was important to show them on their own principles, and according to their own sacred writings, that the great ancestor of all the Levitical community had himself acknowledged his inferiority to one who was declared also in their own writings Psalm 110:1-7 to be like the Messiah, or who was of the same "order." At the same time, the reasoning concedes nothing false; and conveys no wrong impression. It is not mere fancy or accommodation, nor is it framed on allegory or cabalistic principles. It is founded in truth, and such as might be used anywhere, where regard was shown to pedigree, or respect was claimed on account of the illustrious deeds of an ancestor. It would be regarded as sound reasoning in a country like England, where titles and ranks are recognized, and where various orders of nobility exist. The fact that a remote ancestor had done homage or fealty to the ancestor of another class of titled birth, would be regarded as proof of acknowledged inferiority in the family, and might be used with force and propriety in an argument. Paul has done no more than this.
(Several excellent and evangelical commentators explain the passage on the principle of representations, the admission of which relieves it from many difficulties. If we allow that Abraham was the representative of his seed, and of the sons of Levi among the number, then they unquestionably may be said to have paid tithes in him, in a most obvious and intelligible sense. That Abraham is to be here regarded, as not only the natural but covenant head of Israel, is argued from what is said in Psalm 110:6, of his having "had the promises," which promises manifestly did not belong to him alone, but to him and to his seed, Genesis 17:4-9. The land of Canaan never was actually given to Abraham. He obtained the promise or grant of it, as the representative of his posterity, who came to its enjoyment when four hundred years had expired. By those who adopt this view, the passage is supposed to contain an illustration of the manner in which Adam and Christ represent those who respectively belong to them.
And here let it be noticed, that the objection against Abraham's representative character, grounded by our author on the fact, "that there had been no appointment of Abraham to act in that capacity by Levi," might with equal force be urged against the representation of Adam and Christ, which the reader will find established in the supplementary notes on Romans. 5. As to the force of the argument, on this principle, there can be no doubt. If the representative, the covenant, as well as the natural head, of the sons of Levi, paid tithes and acknowledged inferiority to Melchizedek, their inferiority follows as a matter of course. They are supposed to be comprehended in their head. "This," says Mr. Scott, "incontestibly proved the inferiority of the Levitical priesthood to that of the Messiah, nay, its absolute dependence on him, and subserviency to him;" and, we may add, is sound reasoning alike in every country, in Palestine and in ours, in England or America. On the whole we cannot but think that whatever difficulties some may have in admitting the principle of representation here, far greater difficulties lie on the other side.
Even Prof. Stuart, in his celebrated 14th Excursus, (which for ingenuity deserves, perhaps, all the praise awarded by Bloomfield, Barnes, and others,) resolves the apostle's reasoning into a mere "argumentum a.d. hominem," although, in the passage, there is no evidence of any such thing. He has indeed instanced two cases of "argumentum a.d. hominem," or rather two passages, in both of which the same example occurs Matthew 12:27; Luke 11:19. But if the reader consult these passages, he will find that mistake is impossible. The plainest indication is given, that the argument proceeds on the principle of all adversary. It would require no small ingenuity, however, to press this passage into the same rank with those now quoted. It clearly belongs to a different class, and the apostle proceeds with his argument, without the slightest indication that it was grounded rather on what was admitted, than on what was strictly true.)

For he was yet in the loins of his father - That is, Levi was seminally included in Abraham, his forefather.

For he was yet in the loins of his father,.... Abraham; namely, Levi and his whole posterity; which is to be understood seminally, just as all mankind were in the loins of Adam, when he sinned and fell, and so they sinned and fell in him; and so Levi was in Abraham's loins,
when Melchisedec met him; which, as it proves Melchizedek to be greater than Levi, and much more Jesus Christ, who is a priest of his order, which is the grand thing the apostle has in view; so it serves to illustrate several points of doctrine, in which either of the public heads, Adam and Christ, are concerned, with respect to their seed and offspring; such as personal election in Christ, an eternal donation of all blessings of grace to the elect in him, eternal justification in him, the doctrine of original sin, and the saints' crucifixion, burial, resurrection, and session in Christ, and together with him.

in the loins of his father--that is, forefather Abraham. Christ did not, in this sense, pay tithes in Abraham, for He never was in the loins of an earthly father [ALFORD]. Though, in respect to His mother, He was "of the fruit of (David's, and so of) Abraham's loins," yet, being supernaturally, without human father, conceived, as He is above the natural law of birth, so is he above the law of tithes. Only those born in the natural way, and so in sin, being under the curse, needed to pay tithe to the priest, that he might make propitiation for their sin. Not so Christ, who derived only His flesh, not also the taint of the flesh, from Abraham. BENGEL remarks, The blessings which Abraham had before meeting Melchisedec were the general promises, and the special one of a natural seed, and so of Levi; but the promises under which Christ was comprehended, and the faith for which Abraham was so commended, followed after Abraham's meeting Melchisedec, and being blessed by him: to which fact. Genesis 15:1, "After these things," calls our attention. This explains why Christ, the supernatural seed, is not included as paying tithes through Abraham to Melchisedec.