He had a passion for poetry and had read with enthusiasm epics by Milton and plays and sonnets by the master William Shakespeare. The speaker is looking at the night sky, the constellations, relating inspiration to composition through the irrational and symbolic.
As the "fair creature of an hour," his beloved is short-lived just as, by implication, love is.
Keats' reflection on this woman may represent his preoccupation with beauty and his fear of no longer witnessing beauty, in the form of a woman or nature, once he dies. Specifically, the speaker is afraid that he won't be able to write down all the poetry that exists in his head.
But whilst iambic feet are to the fore, complete iambic pentameter lines are in the minority, as you will shortly discover. 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!
The ninth line begins And when I feel Second Quatrain - Lines 5 - 8 Lines 5 and 6 If the first quatrain gives the basic reason for the fears, the second broadens and deepens the process by which that poetic potential the harvest is realised.
He also feared that he would not be able to achieve his full capacity in terms of writing. Line 6 - the first foot maintains the weight of this emotion, a spondee, double stress. Iambic Pentameter : It is a type of meter consisting of five iambs.
The last phrase of the third quatrain leads into the final couplet, in which the speaker comes to terms with the impossibility of attaining romance and glory, and reaches an understanding of the importance and sufficiency of thought.
Lines 7 and 8 The speaker again refers to the end of life and of how this affects his thought processes. The fair creature of an hour is either an actual, beautiful woman he fleetingly met or some imagined lover.