Debatable causes of hallucinations

Probably the common view of hallucinations of the sane, so far as they are recognised at all, is that they are in all cases due to disease or morbid excitement, or at the very least to indigestion. Ask the first twenty rational men you meet how they would account for a phantasmal visitant if they themselves saw one : as many as ten perhaps will answer, “ I should conclude that I had dined or supped too well.” “ Lobster-salad” is an explanation which I have personally heard suggested many times. It may be at once noted, then, as a point of interest—one, moreover, in which the casual and the telepathic classes completely agree—that in not a single instance known to me has the hallucinated person, according to his own account, been suffering at the time from indigestion. Lobster-salad is the parent of nightmares, of massive impressions of discomfort and horror; not, however, as a rule, even in dreamland, of the distinct and minute visualisation, and the clear-cut audition, which constitute the more specific hallucinations of sleep; and certainly not of waking hallucinations. Nor is morbid excitement of a more general sort a frequent, though it is an occasional, condition; and the same may be said of the ordinary nervous exhaustion that follows hard work.

a two-headed lobster, expanding until it covers the text and then disappearing upwards