Artistically Keats's Nightingale Ode is one of his best conceived and most satisfying and as such most discussed poems. However, while its principal theme of the contrast between the permanence of nature and the shortlastingness of the human lot and that of the precarious nature of creative imagination have received wide critical attention, the internal and structural mechanisms of the movement of the thought process and the figures of speech by which those themes and contrasts reveal themselves in a controlled but suggestive manner have not been examined in details. This article provides an original, refreshing, and detailed approach, largely from a New Critical point of view, to those mechanisms in order to show the poem's essential unity beneath its apparent tension, irony, ambiguity, and skepticism, which are indeed part of its aesthetic conception in light of Keats's own poetic and aesthetic ideas. But the most original and scholarly point is that it is rich and comprehensive in bringing together a whole range of possible sources and analogues of the poem, many of which have been suggested here for the first time.