"Has he been at work all night without being conscious of it. Have other spirits been making impressions on his sensorium. Are there faculties in the mind quite separate one from another, which, like the eyes of Argus, may some of them be awake while others are asleep, and is the great faculty of consciousness not perpetually essential to many mental operations?"
— Boswell, James (1740-1795)
(p. 158 in London Magazine)
See also James Boswell, The Hypochondriack, ed. Margery Bailey, 2 vols. (Stanford UP, 1928).