In this continual pursuit of knowledge, and in the contemplation, whether in history or in the world around him, of Christianity as a Life, his main interests more and more lay. In the one we can trace the influence of Hamilton, in the other perhaps that of Neander—the two teachers of his youth who had most deeply impressed him. Relatively to these, Systematic Theology, and even Apologetics, receded into the background. Secure in his "aliquid inconcussum," he came increasingly to regard the life of the individual Christian and the collective life of the Church as the most convincing of all witnesses to the Unseen and the Supernatural.
Meanwhile the apologetic of his own life was becoming ever more impressive. In the years 1886 and 1887 he lost by death several of his dearest friends. In the former year died Dr. W.B. Robertson of Irvine; and, later, Dr. John Ker, who had been his fellow-student at the University and at the Divinity Hall, his neighbour at Alnwick in the early Berwick days, and at last his colleague as a professor in the United Presbyterian College. In the early part of the following year his youngest sister, Agnes, who with her husband, the Rev. J.C. Meiklejohn, had come to live in Edinburgh two years before for the better treatment of what proved to be a mortal disease, passed away. And in the autumn he lost the last and the dearest of the friends that had been left to him in these later years, William Graham. These losses brought him yet closer than he had been before to the unseen and eternal world.
He was habitually reticent about his inner life and his habits of devotion. No one knew his times of prayer or how long they lasted. Once, indeed, his simplicity of character betrayed him in regard to this matter. The door of his retiring-room at the College was without a key, and he would not give so much trouble as to ask for one. So, in order that he might be quite undisturbed, he piled up some forms and chairs against the door on the inside, forgetting entirely that the upper part of it was obscure glass and that his barricade was perfectly visible from without. It need not be said that no one interrupted him or interfered with his belief that he had been unobserved by any human eye. But it did not require an accidental disclosure like this to reveal the fact that he spent much time in prayer. No one who knew him ever so little could doubt this, and no one could hear him praying in public without feeling sure that he had learned how to do it by long experience in the school of private devotion.
Purified thus by trial and nourished by prayer, his character went on developing and deepening. His humility, utterly unaffected, like everything else about him, became if possible more marked. He was not merely willing to take the lowest room, but far happiest when he was allowed to take it. In one of his classes there was a blind student, and, when a written examination came on, the question arose, How was he to take part in it? Principal Cairns offered to write down the answers to the examination questions to his student's dictation, and it was only after lengthened argument and extreme reluctance on his part that he was led to see that the authorities would not consent to this arrangement.
It was the same with his charity. He was always putting favourable constructions on people's motives and believing good things of them, even when other people could find very little ground for doing so. In all sincerity he would carry this sometimes to amusing lengths. Reference has been made to this already, but the following further illustration of it may be added here. One day, when in company with a friend, the conversation turned on a meeting at which Dr. Cairns had recently been present. At this meeting there was a large array of speakers, and a time limit had to be imposed to allow all of them to be heard. One of the speakers, however, when arrested by the chairman's bell, appealed to the audience, with whom he was getting on extremely well, for more time. Encouraged by their applause, he went on and finished his speech, with the result that some of his fellow-speakers who had come long distances to address the meeting were crushed into a corner, if not crowded out. Dr. Cairns somehow suspected that his friend was going to say something strong about this speaker's conduct, and, before a word could be spoken, rushed to his defence. "He couldn't help himself. He was at the mercy of that shouting audience—a most unmannerly mob!" And then, feeling that he had rather overshot the mark, he added in a parenthetic murmur, "Excellent Christian people they were, no doubt!"
But not the least noticeable thing about him remains to be mentioned—the persistent hopefulness of his outlook. This became always more pronounced as he grew older. Others, when they saw the advancing forces of evil, might tremble for the Ark of God; but he saw no occasion for trembling, and he declined to do so. He was sure that the great struggle that was going on was bound sooner or later, and rather sooner than later, to issue in victory for the cause he loved. And although his great knowledge of the past, and his enthusiasm for the great men who had lived in it, might have been expected to draw his eyes to it with regretful longing, he liked much better to look forward than to look back, using as he did so the words of a favourite motto; "The best is yet to be."
All these qualities found expression in a speech he delivered on the occasion of the presentation of his portrait to the United Presbyterian Synod in May 1888. This portrait had been subscribed for by the ministers and laymen of the Church, and painted by Mr. W.E. Lockhart, R.S.A. The presentation took place in a crowded house, and amid a scene of enthusiasm which no one who witnessed it can ever forget. Principal Cairns concluded a brief address thus: "I have now preached for forty-three years and have been a Professor of Theology for more than twenty, and I find every year how much grander the gospel of the grace of God becomes, and how much deeper, vaster, and more unsearchable the riches of Christ, which it is the function of theology to explore. I have had in this and in other churches a band of ministerial brethren, older and younger, with whom it has been a life-long privilege to be associated; and in the professors a body of colleagues so generous and loving that greater harmony could not be conceived. The congregations to which I have preached have far overpaid my labours; and the students whom I have taught have given me more lessons than many books. I have been allowed many opportunities of mingling with Christians of other lands, and have learned, I trust, something more of the unity in diversity of the creed, 'I believe in the Holy Catholic Church.' In that true Church, founded on Christ's sacrifice and washed in His blood, cheered by its glorious memories and filled with its immortal hopes, I desire to live and die. Life and labour cannot last long with me; but I would seek to work to the end for Christian truth, for Christian missions, and for Christian union. Amidst so many undeserved favours, I would still thank God and take courage, and under the weight of all anxieties and failures, and the shadows of separation from loved friends, I would repeat the confession, which, by the grace of God, time only confirms: 'In Te, Domine, speravi; non confundar in aeternum.'"