The extent to which our universe exhibits structure, order and symmetry. If we took a few weeks to teach everyone just how far the rabbit hole goes in terms of what we've discovered and how symmetry principles guide physics, I think that people would be absolutely astonished. Because when you start to see the actual scaffolding of the universe laid out in the human language of mathematics, something becomes clear to you. What that is, each person has to decide for themselves. Some will see God, a Designer. Others will see necessity; others yet will not understand why the existence of structure is something to marvel at in the first place. It takes some base level of math and physics to really appreciate the magic that we've been learning in the last 100 years. Physicists and mathematicians have been guided by ephemeral ideas like "beauty" - an intuition about the aesthetic form of equations and quantities that physical theories should have (according to a subjective viewpoint of a human being). The strange part is that often times, these aesthetic considerations have led people to astounding discoveries.