"Ercole (Hercules) e il centauro Nesso - Roman copy of a Greek original restored by Caccini " (see details) (see related A | B | C | D), 300 BC Giovan Battista Caccini (1556 - 1613) Uffizi Gallery, Florence, Tuscany, Italy
Centaurs are half-horse and half-human creatures. In mythology they were considered to be the offspring of Ixion and Nephele. In modern times, stories about centaurs remind us that to be human we must not behave as "horses" - but apparently there are plenty of humans whose behavior strongly suggest that they may have a horses' ass.
In Medicine, a centaur named Chiron was who trained Aesculapius (Esculapius) in Clinical Manual Arts, in particular Chirurghia, Cirugia, or Surgery and what today is Chiropractic Medicine. (more in overviews and word-notions)
Nessus was killed by Hercules but the blood his spilled was poison - a fantastic story (see other sources) - perhaps the point is "what goes around comes around" ... Hercules killed himself.
Hercules, a mortal, was in essence a brute - a toy of the Olympic deities.