In degree, if not in kind, this wholehearted, lifelong devotion was something new. It was one of Thoreau’s originalities. To what a pitch he carried it, how serious and all-controlling it was, the pages of his journal bear continual witness. His was a Puritan conscience. He could never do his work well enough. After a eulogy of winter buds, “impregnable, vivacious willow catkins, but half asleep along the twigs” (there, again, is fancy of an uncloying type), he breaks out: “How healthy and vivacious must he be who would treat of these things. You must love the crust of the earth on which you dwell more than the sweet crust of any bread or cake; you must be able to extract nutriment out of a sand heap.” “Must” was a great word with Thoreau. In hard times, especially, he braced himself with it. “The winter, cold and bound out as it is, is thrown to us like a bone to a famishing dog, and we are expected to get the marrow out of it. While the milkmen in the outskirts are milking so many scores of cows before sunrise, these winter mornings, it is our task to milk the winter itself. It is true it is like a cow that is dry, and our fingers are numb, and there is none to wake us up.... But the winter was not given us for no purpose. We must thaw its cold with our genialness. We are tasked to find out and appropriate all the nutriment it yields. If it is a cold and hard season, its fruit no doubt is the more concentrated and nutty.” In these winter journalizings, we not only have example and proof of the earnestness with which Thoreau pursued his outdoor studies, but are shown their method and their sufficient object. He was to be a writer, and nature was to be his theme, or, more exactly, his medium of expression. He required, therefore, in the way of raw material, a considerable store of outward knowledge,--knowledge of the outside or aspect of things,--classified, for convenience, as botany, ornithology, entomology, and the like; but after this, and infinitely more than this, he needed a living, deepening intimacy with the life of the world itself. For observation of the ways of plants and animals, of the phases of earth and sky, he had endless patience and all necessary sharpness of sense; work of this kind was easy,--he could do it in some good degree to his satisfaction; the vexatious thing about it was that it readily became too absorbing; but his real work, his _hard_ work, the work that was peculiarly his, that taxed his capacities to the full, and even so was never accomplished, this work was not an amassing of relative knowledge, an accumulation of facts, a familiarizing of himself with appearances, but a perfecting of sympathy, the organ or means of that absolute knowledge which alone he found indispensable, which alone he cared greatly to communicate. There, except at rare moments, he was to the last below his ideal. His “task” was never done. His union with nature was never complete.