The "history of ideas" includes, I would suggest, acts that were common enough in one's surroundings - including (given the hanged man topic) the usage of such for either minor offence (when left hanging from a small tree branch with torso partially on the ground) to acts of torture (which were in former times deemed essential for an admission of guilt to be considered acceptable), religiously motivated executions (such as the all too frequent Jewish hangings), and executions by exposure outside town limits.
As such, some of the important omissions in Teheuti's earlier post include the various dates of imagery shown by mjhurst and others.
With regards to St Teresa, I would personally hope that it is entirely apt and acceptable to have in a discussion forum not only completed inquiries, but suggestions and reflections of the nature: "St Teresa of Avilla talks of mystical experiences in a manner that calls to mind the hanged man - what possible or plausible connection may this have had on the early development of this figure within tarot? Were her views sufficiently known at the time?"
For myself at any rate, such intrusions become seeds of discovery that may lead us into deadends or into avenues that have nought to do with tarot... or, inexplicably (and then transformed to obvious) into finds that shows intrinsic links that (for example in this instance) may even have permitted an understanding of the figure in former times that we currently assume far fetched.
I perhaps should add that I personally do not consider St Teresa's mystical experiential descriptions as influential on either tarot development nor on its early understanding of the imagery - reversed hangings being just too common... it does, however, suggest that given the prevalence of torture, hangings, and the like, 'mystical' or transcended states may similarly have been far more common than we may perhaps credit, and that though the hanged man may at face value be reflective of an abominable atrocity, may also call to mind of those of the period (who survived such) remembrances of transcended (or mystical) states when caused to suffer in extreme conditions.
This is where, for example, considerations of St Teresa (and others) broaden understanding of both the period, but also both the mind-state common enough, and the likely lived scenarios of myriad individuals.