***Note**: This post talks about [dragonglass][1], which may reference various episodes in HBO's *Game of Thrones* (GoT). The only content that's discussed in this OP is directly related to dragonglass, which includes any conversations/events that may directly involve/mention dragon glass.*

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From what I understand, dragonglass is [obsidian][2]. My question is, **does GoT ever actually mention *why* this glass is effective against white walkers?** Is it solely because obsidian is made at high temperatures by volcanoes (with White Walkers being "ice-like")? Or, does it have to do with the origin of White Walkers, with respect to the Children of the Forest?

> A long-forgotten secret is that the Children [of the Forest] actually created the White Walkers as a weapon, by transforming humans into them: this was achieved in a magic ceremony that involved (among other things) plunging a dragonglass shard into a human's chest.

Perhaps, due to the ceremony involving dragonglass, the White Walkers now have a negative affinity towards it?

Aside from these two theories, I've got nothing.. can anyone help in explaining this?

  [1]: http://gameofthrones.wikia.com/wiki/Dragonglass
  [2]: https://en.wikipedia.org/wiki/Obsidian