User blog comment:Da1337wolf/Speculating Aura and Dust/@comment-3146930-20130825003525/@comment-4773581-20130825004711

It's not that Humans didn't know how to use Dust so much as it is they hadn't discovered it before the Grimm got them to look for something that would be able to stop them.

After all, just because it's been there from the start doesn't mean humans have had it from the start.