Originally Posted By: zmjezhd


It had the meaning of amaze in Classical Greek, too, (link). It's interesting that the same construction in Latin exsisto (showing the same archaic reduplication as the Greek form) means rather 'to come, appear; exist' but not 'to amaze'.


Interesting. It seems to have come from the idea of being 'displaced' - taken out of oneself as it were - a similar concept to several English idioms such as 'being beside yourself' (with grief, amazement, etc) or being 'out of your mind.'