"Of other criticisms, flattering and otherwise, I forbear to speak. As regards some of them, indeed, it would be a reproach to that manliness which I have sought to encourage in my pupil to return blow for blow. If the reader be acquainted with them, this will let him know how I regard them; and if he be not acquainted with them, I would recommend him to ignore them, and to form his own judgment of this book. No fair-minded person who reads it will dream that I, in writing it, had a thought of acting otherwise than justly and generously toward my predecessors, the last of whom,[1] to the grief of all who knew him, has recently passed away." I thus show how willing I was three weeks ago to let discussion cease.
How a great and good man regarded this book is shown by the following extract from a letter from the late Prof. Sedgwick, to whom I sent the first draft of the volume. I gather from the "Life and Letters" that he was a friend of Principal Forbes. The extraordinary freshness of his nature breaks through the concluding lines, which, save as an illustration of this, I should hardly have ventured to quote. There are others which I omit for obvious reasons:
"Cambridge, January 29, 1878.
"My dear Professor: I write to thank you for the little book upon the glaciers of the Alps you had the kindness to send to me, and for the instruction and delight its perusal gave me.... It shows a power of putting the subject in the clear, bright colors of daylight before the reader's eyes, and making him feel as if he were your happy companion and fellow-laborer.
This is the language of a philosopher who took my words as they stand, and did not think it necessary "to put that and that together," so as to convert my statements into "straightforward English."
The law of causality is now an a priori dictum of the human mind. There is no spontaneous generation of phenomena; and, like all other things, the book now under consideration had its antecedents. These are in great part to be found in a discussion which occurred twelve years ago regarding the scientific position of a noble but a suffering man. By his unaided genius, Dr. Robert Julius Mayer, of Heilbronn in Germany, reached the heart of a generalization, which the professional hierarchy of science in his day had failed to reach, and which in its later developments ranks as high as the principle of gravitation. For this great Bahnbrecher I sought recognition; but the recognition was by no means immediate, nor was my act applauded by all. Much the reverse. I was accused, not only of want of patriotism, but of "depreciation and suppression." I was charged with ignorance, and an "abuse of language." Every spark of originality was denied to Dr. Mayer. The calculation of the mechanical equivalent of heat, which I had ascribed to him, was claimed for M. Seguin, who, it was alleged, had, three years before Mayer, made the same calculation, and obtained
