When discussing human-made industry, Emerson alludes to the story of Aeolus’s bag in order to emphasize the raw power of steam:
He no longer waits for favoring gales, but by means of steam, he realizes the fable of Æolus’s bag, and carries the two and thirty winds in the boiler of his boat.
In Homer's Odyssey, Aeolus is the king of the winds. Upon meeting Odysseus—the titular character of the Odyssey who is on a quest to return to his home on the island of Ithaca—Aeolus gifts him a bag containing wind so that he may sail home as quickly as possible. However, the Odyssey's story does not end well, for Odysseus's subordinates open the bag thinking it contains treasure, and this blows them off course.
Emerson invokes the comparison between steam-powered boats and Aeolus's bag to emphasize how humans have actively benefited from the powers of nature. Like Odysseus, those who benefit from steam power have mastered a natural resource and made it bend to their will.
Thus, Emerson suggests that humans in the industrial age are as blessed as a Greek hero. The comparison serves to add a mythic quality to both nature and the industrious power of humanity. What was once magic of the imagination to ancient Greeks has become realized because of the ways science has found to utilize the natural world. This allusion is meant to make the reader consider steam power, something somewhat mundane, as a miraculous emblem of how human ingenuity can use nature as a commodity.
The simile that Emerson employs, in which he compares nature to the Saviour's ass, is meant to highlight the importance of nature while also setting it up in a subservient relationship to man:
[Nature] receives the dominion of man as meekly as the ass on which the Saviour rode.
According to the Torah or the Old Testament, the prophet Zechariah wrote that a king would come to the people upon an ass. Riding an ass is fairly standard symbolism for a savior figure, as in the Book of Kings when the legendary King Solomon rides an ass to his God-ordained coronation. So, in the New Testament, when Jesus rides an ass into Jerusalem, he is recognized as the messiah instantly, and the people rejoice.
In the story, the ass is necessary for Jesus's recognition as messiah, just as nature is necessary for man’s health and wellbeing, even if it is in a role of service. This characterization does not necessarily diminish the divinity of nature that Emerson spent so much time establishing, as the service of the ass is not debasing, it is essential. To Emerson, being used is not a sign of something being disposable but rather a sign of something being good.
