By attending to which, ye may understand, pros ho dunasthe anaginoskontes noosai. Erasmus renders it, "from which things, when ye read, ye may understand." But to translate anaginoskein ti as signifying to read is, I think, at variance with Greek syntax. I leave it as a subject of consideration, whether it does not rather signify to attend. The participle would then be connected with the preposition pros, in the commencement of the verse, and the clause would run thus, to which when ye attend, ye may understand If, however, by viewing the verb anaginoskontes, as disjoined from the preposition, you make it signify reading, the meaning will still be, "by reading you may understand according to what I have written;" taking the phrase pros ho, to which, as equivalent to kath ' ho, according to which; but I suggest this merely as a doubtful conjecture. If we adopt the view which is almost universally approved, that the apostle had formerly written to the Ephesians, this is not the only Epistle which we have lost. And yet there is no room for the sneers of the ungodly, as if the Scriptures had been mutilated, or in any part had become imperfect. If we duly consider Paul's earnestness, -- his watchfulness and care, -- his zeal and fervor, -- his kindness and readiness in assisting brethren, -- we shall be led to regard it as highly probable that he would write many epistles, both of a public and private nature, to various places. Those which the Lord judged to be necessary for his church have been selected by his providence for everlasting remembrance. Let us rest assured, that what is left is enough for us, and that the smallness of the remaining number is not the result of accident; but that the body of Scripture, which is in our possession, has been adjusted by the wonderful counsel of God. My knowledge. The frequent mention of this point shews the necessity that the calling of ministers should be firmly believed both by themselves and by their people. But Paul looks more to others than to himself. He had everywhere indeed given great offense by preaching the gospel indiscriminately to Jews and Gentiles, but his solicitude was not chiefly on his own account. There were not a few who, overwhelmed by the slanders of wicked men, began to doubt of his apostleship, and whose faith was consequently shaken. It was this that induced him so frequently to remind the Ephesians that he knew the will and command of God who called him to the office. -- In the mystery of Christ,

Whereby, when ye read - By the bare reading of which you may understand the view which I entertain of the plan of salvation, and the knowledge which I have of God's method of saving people, particularly of his intention in regard to the salvation of the Gentiles.
In the mystery of Christ - This does not refer to anything "mysterious" in the person of Christ; or the union of the divine and human nature in him; or to anything difficult of apprehension in the work of the atonement. It means the hitherto concealed doctrine that through the Messiah, the Gentiles were to be received to the same privileges as the Jews, and that the plan of salvation was to be made equally free for all. This great truth had been hitherto concealed, or but partially understood, and Paul says that he was appointed to make it known to the world. His "knowledge" on the subject, he says, could be understood by what he had said, and from that they could judge whether he was qualified to state and defend the doctrines of the gospel. Paul evidently supposed that the knowledge which he had on that subject was of eminent value; that it was possessed by few; that it was important to understand it. Hence he dwells upon it. He speaks of the glory of that truth. He traces it back to the counsels of God. He shows that it entered into his eternal plans; and he evidently felt that the truth which he had communicated in the former part of this Epistle, was among the most important that could come before the mind.

Whereby, when ye read - When ye refer back to them.
Ye may understand my knowledge - Ye may see what God has given me to know concerning what has been hitherto a mystery - the calling of the Gentiles, and the breaking down the middle wall between them and the Jews, so as to make both one spiritual body, and on the same conditions.

Whereby when ye read,.... The above chapters, and seriously consider what is contained in them:
ye may understand my knowledge in the mystery of Christ of his person, office, and grace; and which knowledge was very large indeed.

understand my knowledge--"perceive my understanding" [ALFORD], or "intelligence." "When ye read," implies that, deep as are the mysteries of this Epistle, the way for all to understand them is to read it (2-Timothy 3:15-16). By perceiving his understanding of the mysteries, they, too, will be enabled to understand.
the mystery of Christ--The "mystery" is Christ Himself, once hidden, but now revealed (Colossians 1:27).