I saw Kean return to the public in ‘Richard III’, and finely he did it, and, at the request of Reynolds, I went to criticize his Luke in Riches. The critique is in to-day's ‘Champion’, which I send you, with the Examiner, in which you will find very proper lamentation on the obsoletion of Christmas Gambols and pastimes: but it was mixed up with so much egotism of that drivelling nature that pleasure is entirely lost. Hone, the publisher’s trial, you must find very amusing; and, as Englishmen, very encouraging — his Not Guilty is a thing, which not to have been, would have dulled still more Liberty’s Emblazoning — Lord Ellenborough has been paid in his own coin — Wooler and Hone have done us an essential service — I have had two very pleasant evenings with Dilke, yesterday and to-day, and am at this moment just come from him, and feel in the humour to go on I spent Friday evening with Wells, and went next morning to see Death on the Pale Horse. It is a wonderful picture, when West’s age is considered; But there is nothing to be intense upon; no woman one feels mad to kiss, no face swelling into reality — The excellence of every art is its intensity, capable of making all disagreeables evaporate, from their being in close relationship with Beauty and Truth. Examine ‘King Lear’, and you will find this exemplified throughout; but in this picture we have unpleasantness without any momentous depth of speculation excited, in which to bury its repulsiveness — The picture is larger than ‘Christ rejected’.

from being incapable of remaining content with half-knowledge — Here, Keats likely refers to one or more of Coleridge’s poems. The prior year (1816), Coleridge had published “Kubla Khan; or A Vision in Dream,” now generally considered one of his greatest works. However, he prefaced it with what was, in effect, an apology, saying that he had begun the poem many years earlier but had never been able to finish it. In that introduction, he explains that while ill he had been prescribed medicine (it was laudanum, a liquid form of opium, and Coleridge tragically became addicted to it) by a doctor and fell asleep reading a book called Purchas’s Pilgrimage, which led to a dream during which he had effortlessly composed “not less than two to three hundred lines.” When he awoke, he began writing those lines down, but he was interrupted by “a person on business from Porlock,” and when he returned he could no longer remember the rest of the poem. Only after the great poet Lord Byron heard Coleridge recite it and insisted Coleridge publish it did he do so, and he even refused to name Byron as the poet for fear of embarrassing him, saying that he was publishing it “at the request of a poet of great and deserved celebrity, and as far as the author’s own opinions are concerned, rather as a psychological curiosity, than on the ground of any supposed poetic merits.”

In the same volume in which Coleridge published “Kubla Khan,” he — also at Byron’s urging — published “Christabel,” a poem about a young noblewoman who goes out in the woods and encounters a supernatural creature, a kind of lesbian vampire named Geraldine. Coleridge had completed the first part of the poem in 1797 and the second part in 1800, but he supposedly had plans for three more parts that he never wrote. At the point the poem ends, Geraldine appears triumphant, and though Coleridge assured readers that all would be well in the end, imagining how he would have brought about that conclusion (given the situation at the end of Part II) is practically impossible. Keats could thus have had this poem in mind instead, or both poems equally, as examples of a fine isolated verisimilitude caught from the Penetralium of mystery that Coleridge is willing to let go by (abandon).