Every enlightened spirit will guess, he implies, that this thing is poetry, and to Poetry personified he addresses his next invocation, declaring that if he can endure the overwhelming favour of her acceptance he will be admitted to 'the fair visions of all places' and will learn to reveal in verse the hidden beauty and meanings of things, in an ascending scale from the playing of nymphs in woods and fountains to 'the events of this wide world,' which it will be given him to seize 'like a strong giant.' At this point a warning voice within him reminds him sadly of the shortness and fragility of life, to which an answering inward voice of gay courage and hope replies. Keats could only think in images, and almost invariably in images of life and action: those here conveying the warning and its reply are alike felicitous:-- Stop and consider! life is but a day; A fragile dew-drop on its perilous way From a tree's summit; a poor Indian's sleep While his boat hastens to the monstrous steep Of Montmorenci. Why so sad a moan? Life is the rose's hope while yet unblown; The reading of an ever-changing tale; The light uplifting of a maiden's veil; A pigeon tumbling in clear summer air; A laughing school-boy, without grief or care, Riding the springy branches of an elm. Then follows a cry for length enough of years (he will be content with ten) to carry out the poetic schemes which float before his mind; and here he returns to his ascending scale of poetic ambitions and sets it forth and amplifies it with a new richness of figurative imagery. First the realms of Pan and Flora, the pleasures of nature and the country and the enticements of toying nymphs (perhaps with a Virgilian touch in his memory from schoolboy days--_Panaque Silvanumque senem nymphasque sorores_--certainly with visions from Poussin's Bacchanals in his mind's eye): then, the ascent to loftier regions where the imagination has to grapple with the deeper mysteries of life and experiences of the soul. Here again he can only shadow forth his ideas by evoking shapes and actions of visible beings to stand for and represent them symbolically. He sees a charioteer guiding his horses among the clouds, looking out the while 'with glorious fear,' then swooping downward to alight on a grassy hillside; then talking with strange gestures to the trees and mountains, then gazing and listening, 'awfully intent,' and writing something on his tablets while a procession of various human shapes, 'shapes of delight, of mystery and fear,' sweeps on before his view, as if in pursuit of some ever-fleeting music, in the shadow cast by a grove of oaks. The dozen lines calling up to the mind's eye the multitude and variety of figures in this procession-- Yes, thousands in a thousand different ways Flit onward--