"Power" stands side by side with the "Holy Ghost." In a sense, the Holy Ghost is the source of all spiritual virtues, and therefore of the very power of which we have been speaking; but the words are probably used here with some narrower meaning. The predominant use of the name in the New Testament bids us think of that divine fervour which the spirit kindles in the soul--that ardour of the new life which Christ Himself speaks of as fire. Paul came to Thessalonica aglow with Christian passion. He took that as a good omen in his work, a sign that God meant well to the Thessalonians. By nature men do not care passionately for each other as he cared for those to whom he preached in that city. They are not on fire with love, seeking each other's good in spiritual things; consumed with fervent longing that the bad should cease from their badness, and come to enjoy the pardon, the purity, and the company of Christ. Even in the heart of apostles--for though they were apostles they were men--the fire may sometimes have burned low, and a mission have been, by comparison, languid and spiritless; but at least on this occasion the evangelists were all on fire; and it assured them that God had a people waiting for them in the unknown city. If "power" and the "Holy Ghost" are in some degree to be judged only by their effects, there can be no question that "much assurance," on the other hand, is an inner experience, belonging strictly to the self-consciousness of the preacher. It means a full and strong conviction of the truth of the gospel. We can only understand this by contrast with its opposite; "much assurance" is the counterpart of misgiving or doubt. We can hardly imagine an apostle in doubt about the gospel--not quite certain that Christ had risen from the dead; wondering whether, after all, His death had abolished sin. Yet these truths, which are the sum and substance of the gospel, seem, at times, too great for belief; they do not coalesce with the other contents of our mind; they do not weave easily into one piece with the warp and woof of our common thoughts; there is no common measure for them and the rest of our experience, and the shadow of unreality falls upon them. They are so great that it needs a certain greatness to answer to them, a certain boldness of faith to which even a true Christian may feel momentarily unequal; and while he is unequal, he cannot do the work of an evangelist. Doubt paralyses; God cannot work through a man in whose soul there are misgivings about the truth. At least, His working will be limited to the sphere of what is certain for him through whom He works; and if we would be effective ministers of the word, we must speak only what we are sure of, and seek the full assurance of the whole truth. No doubt such assurance has conditions. Unfaithfulness of one kind or another is, as our Lord teaches (John vii. 17), the source of uncertainty as to the truth of His word; and