On Tuesday 21 September 1819 Keats wrote to fellow-poet John Hamilton Reynolds:
“How beautiful the season is now—How fine the air—a temperate sharpness about it. Really, without joking, chaste weather—Dian skies—I never liked stubble-fields so much as now—Aye better than the chilly green of the Spring. Somehow, a stubble-field looks warm—in the same way that some pictures look warm. This struck me so much in my Sunday’s walk that I composed upon it.
I hope you are better employed than in gaping after weather. I have been at different times so happy as not to know what weather it was—No, I will not copy a parcel of verses. I always somehow associate Chatterton with autumn. He is the purest writer in the English Language. He has no French idiom or particles, like Chaucer— ’tis genuine English Idiom in English words. I have given up Hyperion —there were too many Miltonic inversions in it—Miltonic verse cannot be written but in an artful, or rather artist’s humour. I wish to give myself up to other sensations. English ought to be kept up. It may be interesting to you to pick out some lines from Hyperion and put a mark × to the false beauty proceeding from art, and one || to the true voice of feeling. Upon my soul, ’twas imagination —I cannot make the distinction—Every now and then there is a Miltonic intonation—But I cannot make the division properly. The fact is, I must take a walk; for I am writing a long letter to George, and have been employed at it all the morning.”
Keats had begun ‘Hyperion’ exactly one year earlier. During those twelve months he wrote practically everything for which he is remembered.