I have this moment received and read from Newman Smyth a flattering note, and a copy of his article in the “Advance.” A very good one it is, and his own thoughts are noteworthy and to the point. President Gilman of the Johns Hopkins sent me a very admiring letter, in which he urges a student’s edition, on thinner paper and paper covers, which he wants to subscribe for. I shall send it to the publisher before long. April 11, 1880. I am amused at Professor ----’s substitution of demiurgism for evolution, reprinted in the “Independent,” and at the coolness with which the professor proclaims that a hypothesis which he thinks is good for nothing else may be good to put against evolutionism. Darwin has sent me advance sheets of his book on Advantage of Crosses (not moral but floral crosses, and not crosses made of flowers, but those made by insects and winds for the benefit of flowers), and I see much in it which you will enjoy. I am too full of work to use it next week, and if you tell me you will come Monday and take it, I will lend it to you for that week. Professor Fisher has sent me an admirable sermon on “The Folly of Atheism.” Have you seen it? ... I would change a word in paragraph seven. If by proof you mean demonstration of its truth, I remark that rational explanation of the phenomena, so far as known, does not prove an hypothesis. Two different hypotheses may do that; and it may long be impossible to get a crucial test. Sincerely yours, A. GRAY. Dr. Gray was at work on another part of the “Synoptical Flora.” Asters had always been his especial study, and a great and puzzling labor, and these few lines tell of his difficulties. TO GEORGE ENGELMANN. April 17, 1880. We heard only incidentally of your accident, and were very sorry. Do be careful. Don’t climb ladders. Leave that to young fellows like me!... I am half dead with Aster. I got on very fairly till I got into the thick of the genus, among what I called Dumosi and Salicifolia. Here I work and work, but make no headway at all. I can’t tell what are species and how to define any of them, nor what the nomenclature is, i. e., what are original names. I will take this group abroad, but it will be just as bad there, unless I can get some settled ideas before I start. I never was so boggled. To-morrow I’ll sit down and study your Pinus paper, which I have not looked at yet, so absorbed have I been.... My old friend John Carey has died, in England, at eighty-three. Schimper, they say, is dead. They go one by one! CAMBRIDGE, May 8. First, thanks for your very lively letter of May 4,--auspicious day, being my wedding-day, thirty-second anniversary.... Yes, we mean to go abroad right after the meeting of American Association, say September 4, to finish Aster, etc.; to stay at least a year. My wife sends best love to you, your daughter, and son, and I join. TO JOHN H. REDFIELD. CAMBRIDGE, April 21, 1880.