There is something almost pathetic in the fact that the birds remain forever the same. You grow old, your friends die or remove to distant lands, events sweep on and all things are changed. Yet there in your garden or orchard are the birds of your boyhood, the same notes, the same calls, and, to all intents and purposes, the identical birds endowed with perennial youth. The swallows, that built so far out of your reach beneath the eaves of your father's barn, the same ones now squeak and chatter beneath the eaves of your barn. The warblers and shy wood birds you pursued with such glee ever so many summers ago, and whose names you taught to some beloved youth who now, perchance, sleeps amid his native hills, no marks of time or change cling to them; and when you walk out to the strange woods, there they are, mocking you with their ever renewed and joyous youth. The call of the high-holes, the whistle of the quail, the strong piercing note of the meadow lark, the drumming of the grouse--how these sounds ignore the years, and strike on the ear with the melody of that springtime when the world was young, and life was all holiday and romance.[82] The twenty years following his first _Atlantic_ paper were the years of his professional life. He left his clerkship at Washington in 1873 to become a national bank inspector, and until 1884, when he finally retired to rural life, he was busy with his duties as receiver of broken banks, examiner of accounts, and financial expert. During the two decades he published his most distinctive nature volumes: _Wake-Robin_, _Winter Sunshine_, _Birds and Poets_, _Locusts and Wild Honey_, and _Pepacton_, a small output for a man between the years of twenty-six and forty-six, yet one that is significant. Not a page of it had been written in haste, not a page that his later hand had found it necessary to revise. The primal freshness of youth is upon the books; they are as full of vitality and sweetness as a spring morning. Doubtless they are all the better for being the enthusiasms of hours stolen from a dry profession. It is tonic to read them. They are never at fault either in fact or in influence; they are the work of a trained observer, a scientist indeed, yet one who has gone to Nature like a priest to the holy of holies with the glow in his heart and the light on his face. During the following decade, or, more exactly, the period between 1884 and 1894, he added four more books, three of them, _Fresh Fields_, _Signs and Seasons_, and _Riverby_, devoted to Nature, though with more and more of the coldly scientific spirit. These with the five earlier volumes stand alone as Burroughs's contribution to the field that he has made peculiarly his own. They contain his freshest and most spontaneous work.