People from different cultural backgrounds (presumably due to differences in their life backgrounds, which, in turn arises from the natural environments they grew up in) see optical illusions differently. This begs the question whether the same illusions would have been seen by people from Amazonian rainforests as the Romans or modern Europeans. This, in turn, implies whether the same sort of trickery, not just in terms of optical illusions, but also the notion of “rationality” generally, is culturally grounded? This, of course, fits into the story about religions above, or the idea of “Biblically-inspired creationism,” however scientifically ungrounded it might be, as a social, cultural, and political force, while no one cares much for Aztec or Iroquois version of creationism.