...there was a tiny creature born into the world. The creature began as a thought, and came into the world in a little bubble, and would live forever.
As the creature grew, the walls of the bubble grew thinner and thinner, so that more and more of the world around it could be seen more clearly and felt more certainly. There was much, of course, that the tiny creature did not know, but its curiosity was unbounded and its ability to learn unceasing.
Sometimes, though, a very confusing thing would happen. Sometimes other creatures, in similar bubbles, would pass by, and bump the tiny little bubbled one. Sometimes it hurt. Sometimes other creatures - these with no bubbles at all around them - would pass by, and these brave ones would point and name things and talk about the world beyond the horizon. And so sometimes the tiny creature thought that the great wide world must be terrifying and full of things that will hurt a body, and sometimes the tiny creature thought that the world was calling out to it, wanting the creature's company, and longing for the creature's un-bubbled footprints to be added to the prints of those who had already been un-bubbled.
The creature grew slowly, and then one day, the bubble popped!
Blinking, it looked around itself, and saw that both the bubbled and the un-bubbled were right. The world had many dangers in it. And the world was a wondrous place waiting to be explored and lived in. And so the grown creature began to walk.
And it walked and walked ... and bumped into things and hurt itself ... and got bumped into and hurt by others ... and walked some more, not quite ready to admit that the dangers were stronger than the adventure. The creature walked until a summit was reached, and from that summit the creature could see far, far away in all directions. And it was then that the creature noticed something about the bubbled creatures.
When the bubbled creatures were small, the bubble was a protection and a filter and a shield against all harsh things. From the summit, this much was obvious. All the smallest creatures had transparent, protective bubbles. But as the creature stood and watched, over and over, it saw that whenever a bubble popped, the same thing would happen. The newly released creatures would invariably get hurt. They would trip - or some other creature would throw something - or they would fall in holes. Something would always happen.
But then some of the injured creatures got up and walked some more. In fact, some of the creatures who had been released and then injured were right then coming up to the summit themselves, and some further along, descending the other side, striding out to the far summits ahead. The creatures who kept walking had learned how not to hurt themselves (mostly), and how to duck whenever something was thrown at them (mostly), and how to avoid stepping into holes (mostly). And when those walking creatures did hurt themselves or stand in the way of projectiles or fall into holes, they just kept going. It wasn't that they didn't get hurt. It was that they learned how to heal.
The perspective from the summit showed the other choice too. The creatures newly popped out of their first bubbles who decided that the vast wide world was too frightening were able to make their own bubbles. They stopped walking. Or they walked in circles. Or they build up all sorts of interconnected bubbles with other frightened creatures. And over time, the walls of the self-built bubbles got thicker and thicker. Whereas the bubbles they all came with had been transparent, the self-made bubbles were of sterner stuff, and over time it thickened. It yellowed. It got odd creases and waves and opaque spot in it.
And then the creature saw the thing that called it to head toward the summits in the distance, no matter what the dangers or the distance would become. The wondering creature saw that the striding walking creatures up ahead were leaving their footprints in the ground. Big and little footprints, deep and shallow footprints, vague and clearly-edged ones - no matter their apparent kinds, all the walking ones made prints.
But the self-bubbled ones never touched the ground at all. And when they died, no one could see that the enclosed creatures had ever touched the earth.