The cloak that I left at Troas - On the situation of Troas, see the notes on Acts 16:8. It was not on the most direct route from Ephesus to Rome, but was a route frequently taken. See also the introduction, section 2. In regard to what the "cloak" here mentioned was, there has been considerable difference of opinion. The Greek word used (φελόνης phelonēs, - variously written φαιλόνης phailonēs, φελόνης phelonēs, and φελώνης phelōnēs), occurs nowhere else in the New Testament. It is supposed to be used for a similar Greek word (φαινόλης phainolēs) to denote a cloak, or great-coat, with a hood, used chiefly on journeys, or in the army: Latin, "penula." It is described by Eschenberg (Man. Class. Lit., p. 209) as a "cloak without sleeves, for cold or rainy weather." See the uses of it in the quotations made by Wetstein, in loc.
Others, however, have supposed that the word means a traveling-case for books, etc. So Hesychius understands it. Bloomfield endeavors to unite the two opinions by suggesting that it may mean a "cloak-bag," and that he had left his books and parchments in it. It is impossible to settle the precise meaning of the word here, and it is not material. The common opinion that it was a wrapper or traveling-cloak, is the most probable; and such a garment would not be undesirable for a prisoner. It should be remembered, also, that winter was approaching 2-Timothy 4:21, and such a cloak would be particularly needed. He had probably passed through Troas in summer, and, not needing the cloak, and not choosing to encumber himself with it, had left it at the house of a friend. On the meaning of the word, see Wetstein, Robinson, Lex., and Schleusner, Lexicon. Compare, also, Suic. Thes ii. 1422. The doubt in regard to what is here meant, is as old as Chrysostom. He says (Homily x. on this Epistle), that the word φελόνην phelonēn denotes a garment - τὸ ἱματίον to himation. But some understood by it a capsula, or bag - γλωσσόκομον glōssokomon," (compare the notes on John 12:6), "in which books, etc. were carried."
With Carpus - Carpus is not elsewhere mentioned. He was evidently a friend of the apostle, and it would seem probable that Paul had made his house his home when he was in Troas.
And the books - It is impossible to determine what books are meant here. They may have been portions of the Old Testament, or classic writings, or books written by other Christians, or by himself. It is worthy of remark that even Paul did not travel without books, and that he found them in some way necessary for the work of the ministry.
Especially the parchments - The word here used (μεμβράνας membranas, whence our word "membrane"), occurs only in this place in the New Testament, and means skin, membrane, or parchment. Dressed skins were among the earliest materials for writing, and were in common use before the art of making paper from rags was discovered. These "parchments" seem to have been something different from "books," and probably refer to some of his own writings. They may have contained notes, memorandums, journals, or unfinished letters. It is, of course, impossible now to determine what they were. Benson supposes they were letters which he had received from the churches; Macknight, that they were the originals of the letters which he had written; Dr. Bull, that they were a kind of common-place book, in which he inserted hints and extracts of the most remarkable passages in the authors which he read. All this, however, is mere conjecture.

The cloak that I left at Troas - Τον φελονην is by several translated bag or portmanteau; and it is most likely that it was something of this kind, in which he might carry his clothes, books, and travelling necessaries. What the books were we cannot tell, it is most likely they were his own writings; and as to the parchments, they were probably the Jewish Scriptures and a copy of the Septuagint. These he must have had at hand at all times. The books and parchments now sent for could not be for the apostle's own use, as he was now on the eve of his martyrdom. He had probably intended to bequeath them to the faithful, that they might be preserved for the use of the Church.

The cloak that I left at Troas with Carpus,.... About the word here rendered a "cloak", interpreters are not agreed: some take it for a garment, and about this they differ; some would have it to be a dignified robe, such as the Roman consuls and senators of Rome wore; which is not likely, this being not suitable to the apostle's character, state, and circumstances. Others take it to be a courser and meaner garment, wore in cold and rainy weather, to preserve from the inclementencies of it; and winter now coming on, 2-Timothy 4:21 the apostle sends for it; which he perhaps had left at Troas in the summer season, as he came: but others take it to be a kind of desk or scrutoire, to put papers in, or a chest for books, a book press; and so the Syriac version renders it; and which agrees with what follows. Jerom understands it of a book itself, of the Hebrew volume of the Pentateuch (g). Troas, where this cloak, or book press, or book was, was a city in Asia Minor, that stood upon, or near the same place where old Troy stood, and from whence it seems to have had its name, and lay in Timothy's way from Ephesus to Rome; See Gill on Acts 16:8, Acts 20:7 and as for Carpus, he was Paul's host when he was at Troas. Some make him to be first bishop of Laodicea, and then of Crete; he is reckoned among the seventy disciples, and is said to be bishop of Berytus in Thrace; See Gill on Luke 10:1.
When thou comest, bring with thee; he would have him call for it at Troas as he came by, and bring it with him:
and the books; that were in it, or were there, besides the Hebrew Pentateuch: the apostle was a great reader of books, of various sorts, both Gentile and Jewish, as appears by his citations out of the Heathen poets, and his acquaintance with Jewish records, Acts 17:28. And though he was now grown old, and near his exit, yet was mindful and careful of his books, and desirous of having them to read; and herein set an example to Timothy and others, and enforced the exhortation he gave him, 1-Timothy 4:13.
But especially the parchments: which might contain his own writings he had a mind to revise before his death, and commit into the hands of proper persons; or some observations which he had made in his travels, concerning persons and things; though it is most likely that these were the books of the Old Testament, which were written on parchments, and rolled up together; and hence they are called the volume of the book; and these the apostle had a special regard for, that whatever was neglected, he desired that these might not, but be carefully brought unto him.
(g) Epist. ad Damas. qu. 2. p. 12. Tom. 3.

cloak . . . I left--probably obliged to leave it in a hurried departure from Troas.
Carpus--a faithful friend to have been entrusted with so precious deposits. The mention of his "cloak," so far from being unworthy of inspiration, is one of those graphic touches which sheds a flood of light on the last scene of Paul's life, on the confines of two worlds; in this wanting a cloak to cover him from the winter cold, in that covered with the righteousness of saints, "clothed upon with his house from heaven" [GAUSSEN]. So the inner vesture and outer garment of Jesus, Paul's master, are suggestive of most instructive thought (John 19:2).
books--He was anxious respecting these that he might transmit them to the faithful, so that they might have the teaching of his writings when he should be gone.
especially the parchments--containing perhaps some of his inspired Epistles themselves.

The cloak - Either the toga, which belonged to him as a Roman citizen, or an upper garment, which might be needful as winter came on. Which I left at Troas with Carpus - Who was probably his host there. Especially the parchments - The books written on parchment.