Do you consider the holding of your Theory of Natural Selection, in its fullest & most unreserved sense, to be inconsistent,—I do not say with any particular scheme of Theological doctrine,—but with the following belief, viz:
That knowledge is given to man by the direct Inspiration of the Spirit of God.
That God is a personal and Infinitely good Being.
That the effect of the action of the Spirit of God on the brain of man is especially a moral effect.
And that each individual man has, within certain limits, a power of choice as to how far he will yield to his hereditary animal impulses, and how far he will rather follow the guidance of the Spirit Who is educating him into a power of resisting those impulses in obedience to moral motives.
The reason why I ask you is this. My own impression has always been,—not only that your theory was quite compatible with the faith to which I have just tried to give expression,—but that your books afforded me a clue which would guide me in applying that faith to the solution of certain complicated psychological problems which it was of practical importance to me, as a mother, to solve. I felt that you had supplied one of the missing links,—not to say the missing link,—between the facts of Science & the promises of religion. Every year’s experience tends to deepen in me that impression.
But I have lately read remarks, on the probable bearing of your theory on religious & moral questions, which have perplexed & pained me sorely. I know that the persons who make such remarks must be cleverer & wiser than myself. I cannot feel sure that they are mistaken unless you will tell me so. And I think,—I cannot know for certain, but I think,—that, if I were an author, I would rather that the humblest student of my works should apply to me directly in a difficulty than that she should puzzle too long over adverse & probably mistaken or thoughtless criticisms.
At the same time I feel that you have a perfect right to refuse to answer such questions as I have asked you. Science must take her path & Theology hers, and they will meet when & where & how God pleases, & you are in no sense responsible for it, if the meeting-point should be still very far off.
Letter from Mary Everest Boole, dated 13th December 1886, addressed to Charles Darwin (online at The Darwin Project).