In October, 1849, Agassiz, in reply to a request from Thoreau that he would lecture in Bangor, sent this characteristic letter:—
"I remember with much pleasure the time when you used to send me specimens from your vicinity, and also our short interview in the Marlborough Chapel.[35] I am under too many obligations of your kindness to forget it. I am very sorry that I missed your visit in Boston; but for eighteen months I have now been settled in Cambridge. It would give me great pleasure to engage for the lectures you ask from me for the Bangor Lyceum; but I find it has been last winter such a heavy tax upon my health, that I wish for the present to make no engagements; as I have some hope of making my living this year by other efforts,—and beyond the necessity of my wants, both domestic and scientific, I am determined not to exert myself; as all the time I can thus secure to myself must be exclusively devoted to science. My only business is my intercourse with nature; and could I do without draughtsmen, lithographers, etc., I would live still more retired. This will satisfy you that whenever you come this way I shall be delighted to see you,—since I have also heard something of your mode of living."
Agassiz had reason indeed to remember the collections made by Thoreau, since (from the letters of Mr. Cabot) they aided him much in his comparison of the American with the European fishes. When the first firkin of Concord fish arrived in Boston, where Agassiz was then working, "he was highly delighted, and began immediately to spread them out and arrange them for his draughtsman. Some of the species he had seen before, but never in so fresh condition; others, as the breams and the pout, he had seen only in spirits, and the little tortoise he knew only from the books. I am sure you would have felt fully repaid for your trouble," adds Mr. Cabot, "if you could have seen the eager satisfaction with which he surveyed each fin and scale." Agassiz himself wrote the same day: "I have been highly pleased to find that the small mud turtle was really the Sternothærus odoratus, as I suspected,—a very rare species, quite distinct from the snapping turtle. The suckers were all of one and the same species (Catastomus tuberculatus); the female has the tubercles. As I am very anxious to send some snapping turtles home with my first boxes, I would thank Mr. T. very much if he could have some taken for me."
Mr. Cabot goes on: "Of the perch Agassiz remarked that it was almost identical with that of Europe, but distinguishable, on close examination, by the tubercles on the sub-operculum.... More of the painted tortoises would be acceptable. The snapping turtles are very interesting to him as forming a transition from the turtles proper to the alligator and crocodile.... We have received three boxes from you since the first." (May 27.) "Agassiz was much surprised and pleased at the extent of the collections you sent during his absence in New York. Among the fishes there is one, and probably two, new species. The fresh-water smelt he does not know. He is very anxious to see the pickerel with the long snout, which he suspects may be the Esox estor, or Maskalongé; he has seen this at Albany.... As to the minks, etc., I know they would all be very acceptable to him. When I asked him about these, and more specimens of what you have sent, he said, 'I dare not make any request, for I do not know how much trouble I may be giving to Mr. Thoreau; but my method of examination requires many more specimens than most naturalists would care for.'" (June 1.) "Agassiz is delighted to find one, and he thinks two, more new species; one is a Pomotis,—the bream without the red spot in the operculum, and with a red belly and fins. The other is the shallower and lighter colored shiner. The four dace you sent last are Leuciscus argenteus. They are different from that you sent before under this name, but which was a new species. Of the four kinds of minnow, two are new. There is a black sucker (Catastomus nigricans), but there has been no specimen among those you have sent, and A. has never seen a specimen. He seemed to know your mouse, and called it the white-bellied mouse. It was the first specimen he had seen. I am in hopes to bring or send him to Concord, to look after new Leucisci, etc." Agassiz did afterwards come, more than once, and examined turtles with Thoreau.
Soon after this scientific correspondence, Thoreau left his retreat by Walden to take the place of Emerson in his household, while his friend went to visit Carlyle and give lectures in England. The letters that follow are among the longest Thoreau ever composed, and will give a new conception of the writer to those who may have figured him as a cold, stoical, or selfish person, withdrawn from society and its duties. The first describes the setting out of Emerson for Europe.
TO SOPHIA THOREAU (AT BANGOR).
Concord, October 24, 1847.
Dear Sophia,—I thank you for those letters about Ktaadn, and hope you will save and send me the rest, and anything else you may meet with relating to the Maine woods. That Dr. Young is both young and green too at traveling in the woods. However, I hope he got "yarbs" enough to satisfy him. I went to Boston the 5th of this month to see Mr. Emerson off to Europe. He sailed in the Washington Irving packet-ship; the same in which Mr. [F. H.] Hedge went before him. Up to this trip the first mate aboard this ship was, as I hear, one Stephens, a Concord boy, son of Stephens the carpenter, who used to live above Mr. Dennis's. Mr. Emerson's stateroom was like a carpeted dark closet, about six feet square, with a large keyhole for a window. The window was about as big as a saucer, and the glass two inches thick, not to mention another skylight overhead in the deck, the size of an oblong doughnut, and about as opaque. Of course it would be in vain to look up, if any contemplative promenader put his foot upon it. Such will be his lodgings for two or three weeks; and instead of a walk in Walden woods he will take a promenade on deck, where the few trees, you know, are stripped of their bark. The steam-tug carried the ship to sea against a head wind without a rag of sail being raised.
I don't remember whether you have heard of the new telescope at Cambridge or not. They think it is the best one in the world, and have already seen more than Lord Rosse or Herschel. I went to see Perez Blood's, some time ago, with Mr. Emerson. He had not gone to bed, but was sitting in the wood-shed, in the dark, alone, in his astronomical chair, which is all legs and rounds, with a seat which can be inserted at any height. We saw Saturn's rings, and the mountains in the moon, and the shadows in their craters, and the sunlight on the spurs of the mountains in the dark portion, etc., etc. When I asked him the power of his glass, he said it was 85. But what is the power of the Cambridge glass? 2000!!! The last is about twenty-three feet long.
I think you may have a grand time this winter pursuing some study,—keeping a journal, or the like,—while the snow lies deep without. Winter is the time for study, you know, and the colder it is the more studious we are. Give my respects to the whole Penobscot tribe, and tell them that I trust we are good brothers still, and endeavor to keep the chain of friendship bright, though I do dig up a hatchet now and then. I trust you will not stir from your comfortable winter quarters, Miss Bruin, or even put your head out of your hollow tree, till the sun has melted the snow in the spring, and "the green buds, they are a-swellin'."