hearts of others, not
least of those who know by experience the pain of speculation, the
truth that he who increaseth knowledge increaseth sorrow. I know you
will indulge these expressions to one more in earnest than in former
years, more philanthropic, more confident that he knows in whom he
has believed, more impressed with the duty of bearing everywhere a
testimony to the convictions which have given him a positive hold
at once of truth and happiness.

"But I check myself in this unwonted strain, which only your
long-continued and singular kindness could have emboldened me to
attempt; and with the utterance of the most fervent wishes for your
health, academical success, and inward light and peace, I remain your
obliged friend and grateful pupil."

To which Sir W. Hamilton replied as follows:--

"EDINBURGH, _Dec_. 4, 1848.

"I feel deeply obliged to you for the kindness of your letter, and
trust that I shall not prove wholly unworthy of the interest you take
in me. There is indeed no one with whom I am acquainted whose
sentiments on such matters I esteem more highly, for there is no one
who, I am sure, is more earnest for the truth, and no one who pursues
it with more independence and, at the same time, with greater
confidence in the promised aid of God. May this promised aid be
vouchsafed to me."[7]

[Footnote 7: _Memoir of Sir W. Hamilton_, pp. 299-301.]

CHAPTER VI

THE CENTRAL PROBLEM

It was confidently expected, not merely by Cairns's personal friends
but by others in a much wider circle, that he would make a name for
himself in the world of letters and speculative thought. It was not
only the brilliance of his University career that led to this
expectation, for, remarkable as that career had been, there have been
many men since his time who, so far as mere prize taking is concerned,
have equalled or surpassed him--men who never aroused and would not
have justified any high-pitched hopes about their future. But Cairns,
in addition to gaining academic distinctions, seems to have impressed
his contemporaries in a quite exceptional degree with a sense of his
power and promise. Professor Masson, writing of him as he was in
his student days, thus describes him: "There was among us one whom
we all respected in a singular degree. Tall, strong-boned, and
granite-headed, he was the student whom Sir William Hamilton himself
had signalised and honoured as already a sterling thinker, and the
strength o