From indications contained in the brief Memoir from which this extract is taken, as well as from references in his correspondence, it would appear that about this time he subjected his religious beliefs to a careful scrutiny in the light cast upon them by his philosophical studies. From this process of testing and strain he emerged with his faith established on a yet firmer basis than before. One result of this experience may perhaps be found in a letter to his father, in which he tells him that he has been weighing the claims of the Christian ministry as his future calling in life. He feels the force of its incomparable attractions, but doubts whether he is fitted in elevation and maturity of character to undertake so vast a responsibility. Besides, he is painfully conscious of personal awkwardness in the common affairs of life, and unfitness for the practical management of business. And so he thinks he will take another year to think of it, during which he will complete his College course. He spent the summer of 1839 with the Donaldson family at their country seat at Auchairn, near Ballantrae, in south Ayrshire, occupying most of his leisure hours in mathematical and physical studies in preparation for the work of the coming winter. In the session of 1839-40, his last at the University, he attended the classes of Natural Philosophy and Rhetoric, taking the first place in the latter and only just missing it in the former. He attended, besides, Sir William Hamilton's private classes, and was much at his house and in his company. In April 1841 he took his M.A. degree, coming out first in Classics and Philosophy, and being bracketed first in Mathematics. Among his fellow-students his reputation was maintained not merely by the honours he gained in the class lists, but by his prowess in the debating arena. Besides continuing his membership in the Metaphysical Society, he had also been, since the spring of 1839, a member of the Diagnostic, one of the most flourishing of the older students' debating societies. Of the Diagnostic he speedily became the life and soul, and discussed with ardour such questions as the Repeal of the Corn Laws, Vote by Ballot, and the Exclusion of Bishops from the House of Lords. One memorable debate took place on the Spiritual Independence of the Church, then the most burning of all Scottish public questions. The position of the Non-Intrusion party in the Established Church was maintained by Cairns's friend Clark, while he himself led on the Voluntary side. The debate lasted two nights, and, to quote the words of one who was present, "Cairns in reply swept all before him, winning a vote from those who had come in curiosity, and securing a large Liberal majority. Amidst a scene of wild enthusiasm we hoisted his big form upon our shoulders, and careered round the old quadrangle in triumph. Indeed he was the hero of our College life, leaving all others far behind, and impressing us with the idea that