that which arises from imagination (Vitista, Chorea imaginativa,
aestimativa), by which the original Dancing Plague is to be
understood. Secondly, that which arises from sensual desires,
depending on the will (Chorea lasciva). Thirdly, that which
arises from corporeal causes (Chorea naturalis, coacta), which,
according to a strange notion of his own, he explained by
maintaining that in certain vessels which are susceptible of an
internal pruriency, and thence produce laughter, the blood is set
in commotion in consequence of an alteration in the vital spirits,
whereby involuntary fits of intoxicating joy and a propensity to
dance are occasioned. To this notion he was, no doubt, led from
having observed a milder form of St. Vitus's dance, not uncommon
in his time, which was accompanied by involuntary laughter; and
which bore a resemblance to the hysterical laughter of the
moderns, except that it was characterised by more pleasurable
sensations and by an extravagant propensity to dance. There was
no howling, screaming, and jumping, as in the severer form;
neither was the disposition to dance by any means insuperable.
Patients thus affected, although they had not a complete control
over their understandings, yet were sufficiently self-possessed
during the attack to obey the directions which they received.
There were even some among them who did not dance at all, but only
felt an involuntary impulse to allay the internal sense of
disquietude, which is the usual forerunner of an attack of this
kind, by laughter and quick walking carried to the extent of
producing fatigue. This disorder, so different from the original
type, evidently approximates to the modern chorea; or, rather, is
in perfect accordance with it, even to the less essential symptom
of laughter. A mitigation in the form of the Dancing Mania had
thus clearly taken place at the commencement of the sixteenth