Dear Tom,-It has long been my wish to make you the patron saint or tutelar divinity of some book of mine, and it has lately occurred to me that it ought to be a book of the desultory and chatty sort that would remind you, in your present exile at the world's eastern rim, of the many quiet evenings of old, when, over a tankard of mellow October and pipe of fragrant Virginia, while Yule logs crackled blithely and the music of pattering sleet was upon the window-pane, we used to roam in fancy through the universe and give free utterance to such thoughts, sedate or frivolous, as seemed to us good. I dare say the present volume may serve as an epitome of many such old-time sessions of sweet discourse, which I trust we shall by and by repeat and renew.But there is one link of association which in my mind especially connects you with the present occasion. My theory of the causes and effects of the prolongation of human infancy, with reference to the evolution of man, was first published in the "North American Review" for October, 1873, when you were the editor of that periodical. The article, which was entitled "The Progress from Brute to Man," was made up of two chapters of my "Outlines of Cosmic Philosophy" (part ii. chaps, xxi., xxii.), which was published a year later, in October, 1874. The value of the theory therein set forth was at once recognized by many leading naturalists. In the address of Vice-President Edward Morse, before the American Association, at its meeting at Buffalo in 1876, my theory receives extended notice as one of the most important contributions yet made to the Doctrine of Evolution; and it is declared that I have given "for the first time a rational explanation of the origin and persistence of family relations, and thence communal relations, and, finally, of society."