Thanks
Mike!
Depending on one's level of devotion, it may also me related to the word "thao", meaning "to suck" (Liddell-Scott) :P
But seriously, "thessastai" is also related to the verb "theto" meaning to "set,put,place" (Liddell-Scott), which in turn is related to "theory". A couple of months ago I speculated in a posting that "theory" itself maybe related to "theos" and "orizein/orion", i.e., "to define one's God". Cant prove this conclusively, but it makes sense to me :)