When the new master arrived upon the scene, he subsided into his original post of assistant. It had been his original intention to go back to the University in November 1836; but as that date approached it became evident that the financial difficulty was not yet removed, so he accepted an engagement to continue his work in Ayton for another year.

His stay in Ayton was a very happy one. He liked his work, and had several warm friends in the village and district. Among these were Mr. Ure, the kindly old minister who had married his parents and baptized himself. Then there was Mr. Stark, minister of another Secession church in the village—a much younger man than Mr. Ure, but a good scholar and a well-read theologian. There was also a fellow-student, Henry Weir, whose parents lived in Berwick, and who used often to walk out to Ayton to see him, Cairns returning the visits, and seeing for the first time, under Weir's auspices, the old Border town in which so much of his own life was to be spent.

All this while he was working hard at his private studies. To these studies he gave all the time that was not taken up by his teaching. He read at his meals, and so far into the night that his aunt became alarmed for his health. He worked his way through a goodly number of the Greek and Latin classics, in copies borrowed from the libraries of the two ministers; and he not only read, but analysed and elaborately annotated what he read. But in the notes of the books read during the year 1837 a change becomes evident. It can be seen that he took more and more to the study of theology and Christian evidences, and his note-books are full of references to Baxter and Jeremy Taylor, to Robert Hall, Chalmers, and Keith.

At length in the summer a crisis was reached. A letter to his father, which has not been preserved, announced that his views and feelings with regard to spiritual things had undergone a great and far-reaching change, and that religion had become to him a matter of personal and paramount concern. Another letter to Henry Weir on the same subject is of great interest. It is written in the unformed and somewhat stilted style which he had not yet got rid of, and, with characteristic reticence, it deals only indirectly with the details of the experience through which he has passed, being in form a disquisition on the importance of personal religion, and a refutation of objections which might occur to his correspondent against making it the main interest of his life.

"My dear Henry," the letter concludes, "I most earnestly wish that you would devote the energies of your mind to the attentive consideration of religion, and I have no doubt that, through the tuition of the Divine Spirit, you would speedily arrive at the same conviction of the importance of the subject with myself, and then our friendship would, by the influence of those feelings which religion implants, be more hallowed and intimate than before. I long ardently to see you."

The experience which has thus been described caused no great rift with the past, nor did it produce any great change in his outward life. He did not dedicate himself to the ministry; he did not, so far as can be gathered, even become a member of the Church; and although for a short time he talked of concentrating his energies on the Greek Testament, to the disparagement of the Greek and Latin classical writers, within two months we find him back at his old studies and strenuously preparing for the coming session at College. But a new power had entered into his life, and that power gradually asserted itself as the chief and dominating influence there.

Cairns returned to the University in the late autumn of 1837, enrolling himself in the classes of Latin, Greek, and Logic. Although he maintained his intimacy with his uncle's family, he now went into lodgings in West Richmond Street, sharing a room with young William Inglis, son of the minister at Stockbridge, then a boy at the High School. Here is the description he gives to his parents of his surroundings and of the daily routine of his life: "The lodging which we occupy is a very good room, measuring 18 feet by 16 feet, in every way neat and comfortable. The walls are hung with pictures, and the windows adorned with flowers. The rent is 3s. 6d., with a promise of abatement when the price of coals is lowered. This is no doubt a great sum of money, but I trust it will be amply compensated by the honesty, cleanliness, economy, and good temper of the landlady.... I shall give you the details of my daily life:—Rise at 8; 8.30-10, Latin class; 10-1, private study; 1-2, Logic; 2-3, Greek class; 4-12.30, private study. As to meals—breakfast on porridge and treacle at 8.15; dine on broth and mutton, or varieties of potatoes with beef or fish, at 3.15; coffee at 7; if hungry, a little bread before bed. I can live quite easily and comfortably on 3s. or 3s. 6d. per week, and when you see me you will find that I have grown fat on students' fare."

At the close of the session he thus records the result of his work in one of the classes:—

"There is a circumstance which but for its connection with the subject of clothes I should not now mention. You are aware that a gold medal is given yearly by the Society of Writers to the Signet to the best scholar in the Latin class. Five are selected to compete for it by the votes of their fellow-students. Having been placed in the number a fortnight ago, I have, after a pretty close trial, been declared the successful competitor. The grand sequence is this, that at the end of the session I must come forward in the presence of many of the Edinburgh grandees and deliver a Latin oration as a prelude to receiving the medal. Although I have little fear that an oration will be forthcoming of the ordinary length and quality, I doubt that the trepidation of so unusual a position will cause me to break down in the delivery of it; but we shall see. The reference of this subject to the clothes you will at once discern. The trousers are too tight, and an addition must be made to their length. The coat is too wide in the body, too short and tight in the sleeves, and too spare in the skirt. As to my feelings I shall say nothing, because I do not look upon the honour as one of a kind that ought to excite the least elation ... I would not wish you to blazon it, nor would I, but for the cause mentioned, have taken any notice of it."

Besides this medal, he obtained the first place in the Greek class. In Logic he stood third, and he carried off a number of other prizes. He had been in every way the better for the interruption in his course; his powers had matured, he knew what he could do, and he was able to do it at will, and from this point onward he was recognised as easily the first man of his time in the University. But he had now to look about him for employment in the vacation; and for a while, in spite of the successes of the past session, he was unable to find it, and was glad to take some poorly paid elementary teaching. But at length, by the good offices of one of the masters in the Edinburgh Academy, backed by the strong recommendation of Professor Pillans, he became tutor in the family of Mr. John Donaldson, W.S., of whose house, 124 Princes Street, he became an inmate. "What I want," said Mr. Donaldson to the professor, "is a gentleman." "Well," replied Pillans, "I am sending you first-rate raw material; we shall see what you will make of it." He retained this situation till the close of his University course, to the entire satisfaction of his employer and his family, and with great comfort to himself—the salary being more than sufficient for his simple needs.