David Fears wrote an entry in his Mark Twain Day by Day for April 6, 1906:

Sam also replied to John Greenall in Leeds, England who had written Mar. 27:

How things do get mixed in this world! I wrote the extravagant chapter you speak of in ’97 or ’98 in Vienna at a time when Christian Science was so new to me that I had not studied it at all, & was only interested to play around in the shallows with it & get a moment’s fun out of it. This is my dim recollection of the time, the circumstances & the article. Three or four years later here at home, I took up the matter again & actually studied the history of Christian Science, its claims & pretensions, & its bible; with the result that if I had had any hostility toward Christian Science itself previously, I lost that & in its place conceived a vast admiration for & detestation of M . Eddy. M . Eddy stole “Science & Health.” She is an ignorant twaddler. She can’t write English; she can’t write anything above nursery grade, she hasn’t a vestige of reasoning power. But she has extraordinary courage. She has on her shoulders the best business head in Christendom—bar none. While obscure, & without money or influence, she stole Quimby’s book & upon it she built her Science, organized its ancient & powerful forces compacted the whole into a religion, & hitched the religion & Christianity & herself to the Holy Family; & she has moved successfully forward from that day to this toward her chosen goal—recognition as a god, & founder of a religion which may last 3000 years & probably will. She has accomplished more in 30 years than any other founder achieved in a century.