When I have fears that I may cease to be
Before my pen has glean’d my teeming brain,
Before high piled books, in charact’ry,
Hold like rich garners the full-ripen’d grain;
When I behold, upon the night’s starr’d face,
Huge cloudy symbols of a high romance,
And think that I may never live to trace
Their shadows, with the magic hand of chance;
And when I feel, fair creature of an hour!
That I shall never look upon thee more,
Never have relish in the faery power
Of unreflecting love!—then on the shore
Of the wide world I stand alone, and think
Till Love and Fame to nothingness do sink.
The speaker in this poem is Keats, reflecting on his thoughts about the end of his life.
Basically, Keats is expressing his thoughts of the end of his life. He thinks about before his "pen has gleaned [his] teeming brain" (before he can write or express everything his mind can create - L2) and how he may never look upon nature and the night sky. Keats comes to realize that in the end, love and fame "to nothingness do sink" (L 14), or in other words mean nothing in relation to life's beauties (like creation/expression and the stars) and life itself.
Keats uses imagery to describe the nature he may never again look upon. In lines 5-6, Keats talks about the night sky, personifying night with its "starred face". Keats also references the supernatural power of love in nature (being spontaneous, adventurous, and free-spirited). Ending the poem standing alone on "the shore of the wide world", Keats emphasizes his feeling of solitude in a pensive mood. This strengthens the effect of the possible end to one's life both for the narrator and the reader, and also hels support Keats' claim that love and fame is very small when compared to the overall greatness of being alive.