Slowly raising the temperature allows a frog submerged in water to get accustomed to its ever-worsening condition until it gets cooked to death. So goes folk wisdom regarding how to cook a frog. Though a pointless exercise, it does serve as a good metaphor for how countries gradually advance on the road to tyranny — in very small, nearly imperceptible steps.
But it is possible to notice small objects and minute changes if one gets sensitized to them. It is hard to notice a commercial jetliner at cruising altitude from the ground without its telltale vapor trail. However, after someone points it out to you, it’s easy enough to track the nearly invisible object in the sky if you focus on it.