brutum hominis
Note by H Craik to chapter 3 of Battle of the Books

The elementary principle of man, without the ' plastic' of the soul. The notion is first suggested by the passage in the Phaedo (81), where the lower and more grovelling souls are said to haunt the neighbourhood of tombs and sepulchres, being not entirely detached from the earthly element. Milton reproduces the Platonic notion in Comus (470) —

Such are those thick and gloomy shadows damp
Oft seen in charnel vaults and sepulchres
Lingering, and sitting by a new-made grave;
As loth to leave the body that it loved,' etc.

Dr. Henry More, the Platonist, in his Immortality of the Soul, (Bk. II. ch. xvi), quaintly expresses the notion that bodies 'lately dead, or as fresh as those that are but newly dead,' may facilitate the appearance of the souls of those that are gone, 'and so invite them (i. e. the ghosts) to play tricks when they can do it at so cheap a rate.' Sir T. Brown (Religio Medici) thinks they are not the souls of the dead, 'but unquiet walks of devils,'who choose the cemeteries as 'dormitories of the dead, where the Devil beholds with pride his spoils and trophies.' Sir Kenelm Digby, in his Observations on the Religio Medici, leans to More's view rather than Brown's, and reproduces the idea of Plato, that those 'terrene' souls that 'go out of their bodies with affection to the things they left behind them,' appear in 'cemeteries and charnel-houses.'

These variations in the fancy are interesting, as they shew us where Swift's reading lay.