Your clear exposition of the rhythmic curve of sex-feeling and of the misinterpretation on the part of so many husbands of what they call their wives' contrariness, arising from their ignorance of its existence, should bring happiness to many married couples whose lives are drifting apart through want of knowledge. In the exercise of my ministry I have repeatedly traced the beginnings of the rift to this want of knowledge and consequently of sympathy. So far we are in complete agreement, but our ways part when you treat of birth control. You write primarily as a scientist (though a very human scientist), and so you are naturally mainly occupied with the facts and conditions of what I may call our earth-life. I, on the other hand, writing as a Catholic, regard our earth-life as essentially and inseparably connected with an eternal existence which reaches out beyond the grave. I look on this life as utterly meaningless in itself, as a period which is simply and solely a means to an end--Eternity--a period of which all the circumstances of pleasure and pain can only be explained and rightly used in their relation to this Eternity. Let me take in illustration of my meaning the case you give of the worn-out mother of twelve. The Catholic belief is that the loss of health on her part for a few years of life and the diminished vitality on the part of her later children would be a very small price indeed to pay for an endless happiness on the part of all. In our belief, then, the destruction of one spermatazoon is not the question, but the deliberate prevention of an eternally happy existence which, in the supposition, might arise from its preservation. Holding, as we do, that the marriage-act is the divinely ordained means by which man offers to God the opportunity of creating an immortal being, we do not believe that he may make use of this means and deliberately frustrate it of its end without doing grave wrong. You do me the honour of suggesting that I should write a foreword to your book, but any foreword from me could obviously only derive value from my position as a Catholic priest, and that position is in opposition to this part of your work. I cannot end without thanking you very sincerely for allowing me to read your book. Apart from what, as a Catholic, I object to in it, it contains so much most helpful matter that I feel sure it will bring to many a happiness in married life now wanting through the ignorance and the consequent want of sympathy which you so rightly deplore. Believe me, dear Dr. Stopes, Yours very sincerely, S. ST. JOHN, S.J., C.F. I publish this letter with sincere thanks to Father St. John for his permission to use it.--M. C. S. Reply to Father St. John, S.J. LEATHERHEAD, December 12, 1917. DEAR FATHER ST. JOHN,--