Charles Darwin's grandson is the authorof this lettert to Pearson

2139. ability (setting modesty aside) as a not very firmly anchored quality, it may be doubtful whether there will not be a "diminishing return" in trying the double dose; in fact whether the net intelligence of the world would not be more increased by a less selective marriage. We very much hope that in a few years the experiment will be capable of verification. I am afraid I have cast aside the proper modesty as to myself, but perhaps under the circumstances your letter entitles me to do so. In the meanwhile Nature shows its intentions by making life very pleasant. Believe me Yours very sincerely Charles Darwin [end]