I take the "eastern air" to signify the aura of Eden, but I could be wrong. Here is, perhaps, some useful insight from Saree Makdisi, by way of Edward Said:
As Edward Said has argued, the Orient "as such" only exists--and has only ever existed--asa spatial construction endowed with a series of facts, essences, histories, etc., a space that could be known, controlled, exploited and developed by Europeans. Byron's Orientalism has often been compared to Shelley's, but while the two poets undoubtedly have much in common, I believe that it is of crucial importance to distinguish between Byron's East--as produced in the first two cantos of Child Harold (1812)--and the vision of the East first produced by Shelley in Alastor; or, the Spirit of Solitude (1816). Underlying each of these versions of the Orient there are radically opposed concepts of empire, of Orientalism, and of history--concepts that would become more defined in Shelley's (and, though to a lesser extent, Byron's) later works. What I want to propose in the present essay is that the Oriental space developed in Alastor represents a reclamation of an Oriental terrain from previous visions and versions of the East and its incorporation into the emergent space-time of modernity. Thus it not only anticipates the paradigms of Orientalist discourse associated both with James Mill and with late nineteenth-century English Orientalists [...] but it contributes to the historical production of the Orient as a space for European knowledge, discipline, and control. The version of the Orient that is produced in Childe Harold II--the Orient as refuge from and potential alternative to modernity--was contested and redefined in later spatial productions; its critical and imaginary terrain had to be seized, cleansed, and totally reorganized and reinvented. The Oriental space produced in Al astorsymbolizes the beginning of that reclamation, the production of a new Orient that the poem "discovers," which would later be embellished, developed, augmented, and improved in succeeding visions and versions of the East. (204)
Although Makdisi does not mention Epipsychidion, consider the following lines from the poem and let us see if Makdisi's argument--that there is an imperialist spirit in Shelley's work--applies here:
This isle and house are mine, and I have vowed
Thee to be lady of the solitude.
And I have fitted up some chambers there
Looking towards the golden Eastern air,
And level with the living winds, which flow
Like waves above the living waves below.
I have sent books and music there, and all
Those instruments with which high Spirits call
The future from its cradle, and the past
Out of its grave, and make the present last
In thoughts and joys which sleep, but cannot die,
Folded within their own eternity. (513-24)
The idea of taking possession of one's knowledge from books and applying it to the artistic process implies a certain kind of violence. He declares ownership of the house and the isle and has "sent books and music there," indicating a willingness to cultivate the isle with his own idiosyncratic, civil taste. Just as I have suggested in another page, that in certain instances Shelley is reasserting a masculine assertiveness, he may also be asserting a capitalistic-imperialistic drive that is indicative of the spirit of his times. Although not necessarily intentional--this is a love poem after all--the unconscious, imperialist language has crept into Shelley's vernacular while he was attempting to merely portray an ideal, aesthetical setting for himself and his lover. I am yet to find any essays about imperialism and Epipsychidion, but I think I may have found a possible connection. For anyone who is interested in this topic, I believe Edward Said's Orientalism and Alan Richardson and Sonia Hofkosh's collection of essays--Romanticism, Race, and Imperial Culture--would be an excellent beginning.
Let us look more closely at some of the statements Shelley makes in A Defence of Poetry--which he wrote soon after Epipsychidion--to examine the proactive, legislative assertiveness he regards true poets possess:
But Poets, or those who imagine and express this indestructible order, are not only the authors of language and of music, of the dance and architecture and statuary and painting; they are the institutors of laws |&| the founders of civil society and the inventors of the arts of life and the teachers, who draw into a certain propinquity with the beautiful and the true that partial apprehension of the agencies of the invisible world which is called religion. §27 Hence all original religions are allegorical or susceptible of allegory, and like Janus have a double face of false and true. §28 Poets, according to the circumstances of the age and nation in which they appeared were called in the earlier epochs of the world legislators or prophets: a poet essentially comprises and unites both these characters. §29 For he not only beholds intensely the present as it is, and discovers those laws according to which present things ought to be ordered, but he beholds the future in the present, and his thoughts are the forms of {{Sig. 2v}} the flower and the fruit of latest time. §30 Not that I assert poets to be prophets in the gross sense of the word, or that they can fortell the form as surely as they foreknow the spirit of events: such is the pretence of superstition which would make poetry an attribute of prophecy, rather than prophecy an attribute of poetry. §31 A Poet participates in the eternal, the infinite and the one; as far as relates to his conceptions time and place and number are not. §32 The grammatical forms which express the moods of time, and the difference of persons and the distinction of place are convertible with respect to the highest poetry without injuring it as poetry, and the choruses of Æschylus, and the book of Job, and Dante's Paradise would afford more than any other writings examples of this fact, if the limits of this paper did not forbid citation. §33 The creations of sculpture, painting and music are illustrations still more decisive. (par. 4)
The amount of power that Shelley assigns to the poet has some dangerous implications, implications that can be taken literally. Think about the ideological/dangerous/poetical visions that some leaders over the centuries have had. Although Shelley certainly is responding to the marginalization of the poet and, thus, his posturing is a bit theatrical, the imperialistic implications within the language is problematic.
Makdisi, Saree. "Versions of the East: Byron, Shelley, and the Orient." Romanticism, Race, and Imperial Culture, 1780-1834. Ed. Alan Richardson and Sonia Hofkosh. Bloomington: Indiana UP, 1996. 203-36.
Shelley, Percy. A Defence of Poetry. Representative Poetry Online. 2004. Web Development Group, Information Technology Services, University of Toronto Libraries. 25 April 2004 <http://eir.library.utoronto.ca/rpo/display/displayprose.cfm?prosenum=6>.