. . .Your Nomenclator frightens me with its double entries. The Milky Way must have crossed your path, for you seem to be dealing with nebulae which you are trying to resolve into stars. For pity's sake husband your strength. You treat this journey as if it were for life. As to finishing,—alas! my friend, one does not finish. Considering all that you have in your well-furnished brain beside your accumulated papers, half the contents of which you do not yourself know, your expression "aufraumen,"—to put in final order, is singularly inappropriate. There will always remain some burdensome residue,—last things not yet accounted for. I beg you, then, not to abuse your strength. Be content to finish only what seems to you nearest completion,—the most advanced of your work.
Your letter reached me, unaccompanied, however, by the books it announces. They are to come, no doubt, in some other way. Spite of the demands made upon me by the continuation of my "Cosmos," I shall find time to read and profit by your introduction to the Old Red. I am inclined to sing hymns of praise to the Hyperboreans who have helped you in this admirable work. What you say of the specific difference in vertical line and of the increased number of biological epochs is full of interest and wisdom. No wonder you rebel against the idea that the Baltic contains microscopic animals identical with those of the chalk! I foresee, however, a new battle of Waterloo between you and my friend Ehrenberg, who accompanied me lately, just after the Victoria festivals, to the volcanoes of the Eifel with Dechen. Not an inch of ground without infusoria in those regions! For Heaven's sake do not meddle with the infusoria before you have seen the Canada Lakes and completed your journey. Defer them till some more tranquil period of your life. . .I must close my letter with the hope that you will never doubt my warm affection. Assuredly I shall find no fault with any course of lectures you may give in the new world, nor do I see the least objection to giving them for money. You can thus propagate your favorite views and spread useful knowledge, while at the same time you will, by most honorable and praiseworthy means, provide additional funds for your traveling expenses. . .
The following correspondence with Professor Adam Sedgwick is of interest, as showing his attitude and that of Agassiz toward questions which have since acquired a still greater scientific importance.
PROFESSOR ADAM SEDGWICK TO LOUIS AGASSIZ.
TRINITY COLLEGE, CAMBRIDGE, April 10, 1845.
MY DEAR PROFESSOR,
The British Association is to meet here about the middle of June, and I trust that the occasion will again bring you to England and give me the great happiness of entertaining you in Trinity College. Indeed, I wish very much to see you; for many years have now elapsed since I last had that pleasure. May God long preserve your life, which has been spent in promoting the great ends of truth and knowledge! Your great work on fossil fishes is now before me, and I also possess the first number of your monograph upon the fishes of the Old Red Sandstone. I trust the new numbers will follow the first in rapid succession. I love now and then to find a resting-place; and your works always give me one. The opinions of Geoffroy St. Hilaire and his dark school seem to be gaining some ground in England. I detest them, because I think them untrue. They shut out all argument from DESIGN and all notion of a Creative Providence, and in so doing they appear to me to deprive physiology of its life and strength, and language of its beauty and meaning. I am as much offended in taste by the turgid mystical bombast of Geoffroy as I am disgusted by his cold and irrational materialism. When men of his school talk of the elective affinity of organic types, I hear a jargon I cannot comprehend, and I turn from it in disgust; and when they talk of spontaneous generation and transmutation of species, they seem to me to try nature by an hypothesis, and not to try their hypothesis by nature. Where are their facts on which to form an inductive truth? I deny their starting condition. "Oh! but" they reply, "we have progressive development in geology." Now, I allow (as all geologists must do) a KIND OF PROGRESSIVE DEVELOPMENT. For example, the first fish are below the reptiles; and the first reptiles older than man. I say, we have successive forms of animal life adapted to successive conditions (so far, proving design), and not derived in natural succession in the ordinary way of generation. But if no single fact in actual nature allows us to suppose that the new species and orders were produced successively in the natural way, how did they begin? I reply, by a way out of and above common known, material nature, and this way I call CREATION. Generation and creation are two distinct ideas, and must be described by two distinct words, unless we wish to introduce utter confusion of thought and language. In this view I think you agree with me; for I spoke to you on the subject when we met (alas, TEN years since!) at Dublin. Would you have the great kindness to give me your most valuable opinion on one or two points?
(1.) Is it possible, according to the known laws of actual nature, or is it probable, on any analogies of nature, that the vast series of fish, from those of the Ludlow rock and the Old Red Sandstone to those of our actual seas, lakes, and rivers, are derived from one common original low type, in the way of development and by propagation or natural breeding? I should say, NO. But my knowledge is feeble and at second-hand. Yours is strong and from the fountain-head.
(2.) Is the organic type of fish higher now than it was during the carboniferous period, when the Sauroids so much abounded? If the progressive theory of Geoffroy be true, in his sense, each class of animals ought to be progressive in its organic type. It appears to me that this is not true. Pray tell me your own views on this point.
(3.) There are "ODD FISH" (as we say in jest) in the Old Red Sandstone. Do these so graduate into crustaceans as to form anything like such an organic link that one could, by generation, come naturally from the other? I should say, NO, being instructed by your labors. Again, allowing this, for the sake of argument, are there not much higher types of fish which are contemporaneous with the lower types (if, indeed, they be lower), and do not these nobler fish of the Old Red Sandstone stultify the hypothesis of natural generative development?