16.3 Early in the morning, while all things are crisp with frost, men come with fishing-reels and slender lunch, and let down their fine lines through the snowy field to take pickerel and perch; wild men, who instinctively follow other fashions and trust other authorities than their townsmen, and by their goings and comings stitch towns together in parts where else they would be ripped. They sit and eat their luncheon in stout fear-naughts on the dry oak leaves on the shore, as wise in natural lore as the citizen is in artificial. They never consulted with books, and know and can tell much less than they have done. The things which they practice are said not yet to be known. Here is one fishing for pickerel with grown perch for bait. You look into his pail with wonder as into a summer pond, as if he kept summer locked up at home, or knew where she had retreated. How, pray, did he get these in midwinter? Oh, he got worms out of rotten logs since the ground froze, and so he caught them. His life itself passes deeper in nature than the studies of the naturalist penetrate; himself a subject for the naturalist. The latter raises the moss and bark gently with his knife in search of insects; the former lays open logs to their core with his axe, and moss and bark fly far and wide. He gets his living by barking trees. Such a man has some right to fish, and I love to see nature carried out in him. The perch swallows the grub-worm, the pickerel swallows the perch, and the fisher-man swallows the pickerel; and so all the chinks in the scale of being are filled.
This man, Thoreau's answer to Jefferson's yeoman farmer, was soon to become an endangered species, and probably almost extinct by the end of the century. The Indian gave Thoreau an even better opportunity to admire "wild men" whose knowledge is not known by the world or written down.
Concerning measuring the depth of Walden Pond, my guess is that Thoreau loved doing this stuff so much that he could still think of it as goofing off in some way. It was pleasure, whereas to the rest of us, such a physical and intellectaul feat would seem like work. Yet the townspeople still thought he was out there vegetating, apparently. He didn't seem to care if they thought so.