In his published works he was reticent on the matter of religion, and what he has left on the subject was not written with a view to publication. (As an exception may be mentioned, a few words of concurrence with Dr. Abbot's 'Truths for the Times,' which my father allowed to be published in the "Index".) I believe that his reticence arose from several causes. He felt strongly that a man's religion is an essentially private matter, and one concerning himself alone. This is indicated by the following extract from a letter of 1879:--(Addressed to Mr. J. Fordyce, and published by him in his 'Aspects of Scepticism,' 1883.) "What my own views may be is a question of no consequence to any one but myself. But, as you ask, I may state that my judgment often fluctuates...In my most extreme fluctuations I have never been an Atheist in the sense of denying the existence of a God. I think that generally (and more and more as I grow older), but not always, that an Agnostic would be the more correct description of my state of mind." He naturally shrank from wounding the sensibilities of others in religious matters, and he was also influenced by the consciousness that a man ought not to publish on a subject to which he has not given special and continuous thought. That he felt this caution to apply to himself in the matter of religion is shown in a letter to Dr. F.E. Abbot, of Cambridge, U.S. (September 6, 1871). After explaining that the weakness arising from his bad health prevented him from feeling "equal to deep reflection, on the deepest subject which can fill a man's mind," he goes on to say: "With respect to my former notes to you, I quite forget their contents. I have to write many letters, and can reflect but little on what I write; but I fully believe and hope that I have never written a word, which at the time I did not think; but I think you will agree with me, that anything which is to be given to the public ought to be maturely weighed and cautiously put. It never occurred to me that you would wish to print any extract from my notes: if it had, I would have kept a copy. I put 'private' from habit, only as yet partially acquired, from some hasty notes of mine having been printed, which were not in the least degree worth printing, though otherwise unobjectionable. It is simply ridiculous to suppose that my former note to you would be worth sending to me, with any part marked which you desire to print; but if you like to do so, I will at once say whether I should have any objection. I feel in some degree unwilling to express myself publicly on religious subjects, as I do not feel that I have thought deeply enough to justify any publicity." I may also quote from another letter to Dr. Abbot (November 16, 1871), in which my father gives more fully his reasons for not feeling competent to write on religious and moral subjects:--