Some of this essay has to do with the provenance of the 'heroic idyll' itself:
Idyllium, ut quibusdam videtur, heroica esse non potest. Veteres alia fuisse sententia versus quo unico scribitur declarat. Talia sunt Theocriti quaedam, ejusdemque esset generis Catullianum illud de nuptiis Pelei et Thetidis, nisi pepli descriptio intercedisset; ea non tantum episodia est sed pars major ut et melior poematis. Ex Ovidio excerperemus plurima.But more interesting, perhaps, is the aesthetic rationale of Landor's own Latin verse; which is to say, his forceful linking of personal morality and great art. He attacks Byron in these terms:
[The Idyll, according to some, cannot be heroic. Only one exception to this rule is admitted in classical literature. That is the example of Theocritus, although something similar could be said of the Catullus’s ‘Marriage of Peleus and Thetis’ (unless that poem's famous description of a robe might persuade us otherwise); for it is more than just a collection of episodes, and is rather part of a larger, more coherent version. And from Ovid a great many examples may be chosen.]
Summu poetæ in omni poetarum sæculo viri fuerunt probi: in nostris id vidimus et videmus; neque alius est error a veritate longius quam magna ingenia magnis necessario corrumpi vitiis. Secundo plerique posthabent primum, hi malignitate, illi ignorantia, et quum aliquem inveniunt styli morumque vitiis notatum, nec inficetum tamen nec in libris edendis parcum, eum stipant, prædicant, occupant, amplectuntur. Si mores aliquantulum vellet, corrigere, si stylum curare paululum, si fervido ingenio temperare, si moræ tantillum interponere, tum ingens nescio quid et vere epicum, quadraginta annos natus, procuderet. Ignorant vero fabriculis non indicari vires, impatientiam ab imbecillitate non differre; ignorant a levi homine et inconstante multa fortasse scribi posse plusquam mediocria, nihil compositum, arduum, æternum. Si mores aliquantulum vellet, corrigere, si stylum curare paululum, si fervido ingenio temperare, si moræ tantillum interponere, tum ingens nescio quid et vere epicum, quadraginta annos natus, procuderet.
[‘the ancient poet was a man of supreme moral probity: but amongst our poets we have seen (and we continue to see) great minds necessarily alienated from the truth because corrupted by great vices. A great many second-rank writers follow this first-rank one [ie Byron], some from wickedness, others ignorance, and when they encounter his viciousness (both stylistic and moral), not being yet corrupted either in their lives or in their books, they mob him, plundering him, possessing him, twining themselves around him. This poet should correct his debased morals if he wishes to improve his style even a little bit—if he could hold back his fervor, if he could manifest even the smallest amount of moral probity, then who knows how truly great an epic, now that he is in his fourth decade, he might produce! However unsure of his strength, impatience being nothing more than weakness; unsure whether so light and inconstant a man could write more modestly, the arduous, endless labour of such composition has not been undertaken.’]