While the chapter does deal with the ecstasy produced in the narrator by various sounds, the title has a broader significance. Thoreau is stressing the primary value of immediate, sensual experience; to live the transcendental life, one must not only read and think about life but experience it directly.
As the chapter opens, we find the narrator doing just that. He is awake to life and is "forever on the alert," "looking always at what is to be seen" in his surroundings. Thus he opens himself to the stimulation of nature. The result, by now, is predictable, and the reader should note the key metaphors of rebirth (summer morning, bath, sunrise, birds singing). The fact that he spiritually "grew in those seasons like corn in the night" is symbolized by an image of nature's spring rebirth: "The large buds, suddenly pushing out late in the spring from dry sticks which had seemed to be dead, developed themselves as by magic into graceful green and tender boughs." Like nature, he has come from a kind of spiritual death to life and now toward fulfillment.
The locomotive's interruption of the narrator's reverence is one of the most noteworthy incidents in Walden. It is very significant that it is an unnatural, mechanical sound that intrudes upon his reverence and jerks him back to the progressive, mechanical reality of the nineteenth century, the industrial revolution, the growth of trade, and the death of agrarian culture. It is interesting to observe the narrator's reaction to this intrusion. He is an individual who is striving for a natural, integrated self, an integrated vision of life, and before him are two clashing images, depicting two antithetical worlds: lush, sympathetic nature, and the cold, noisy, unnatural, inhuman machine. He has criticized his townsmen for living fractured lives and living in a world made up of opposing, irreconcilable parts, yet now the machine has clanged and whistled its way into his tranquil world of natural harmony; now he finds himself open to the same criticism of disintegration. Being one who is always "looking at what is to be seen," he cannot ignore these jarring images. So, he attempts to use the power within — that is, imagination — to transform the machine into a part of nature. If this works, he will again have a wholesome, integrated vision of reality, and then he may recapture his sense of spiritual wholeness. Therefore, he imaginatively applies natural imagery to the train: the rattling cars sound "like the beat of a partridge." Once again he uses a natural simile to make the train a part of the fabric of nature: "the whistle of the locomotive penetrates my woods summer and winter, sounding like the scream of a hawk sailing over some farmer's yard." Having thus engaged his poetic faculties to transform the unnatural into the natural, he continues along this line of thought, moving past the simple level of simile to the more complex level of myth. And his mythological treatment of the train provides him with a cause for optimism about man's condition: "When I hear the iron horse make the hills echo with his snort-like thunder, shaking the earth with his feet, and breathing fire and smoke from his nostrils . . . it seems as if the earth had got a race now worthy to inhabit it."
