It may be hard for an egg to turn into a bird: it would be a jolly sight harder for it to learn to fly while remaining an egg. We are like eggs at present. And you cannot go on indefinitely being just an ordinary, decent egg. We must be hatched or go bad.
There is certain comfort in incubating in the nest, snuggled warm under a fluffy breast, satisfied with the status quo. I tend toward perpetual nesting myself, preferring home to travel, too easily contented with the familiar rather than stretching into uncharted territory.
But eventually the unhatched egg gets the boot, even by its parents. When there are no signs of life, no twitches and wiggles and movement inside, it is doomed to rot. And we all know nothing is worse than a rotten egg. Nothing.
So we must chip away and crack open our comfy shell, leaving the fragments behind. Feeble, weak and totally dependent on the grace of others to feed and protect us, we are freed of the confinement of the sterility of the commonplace and loosed upon an unsuspecting world.
Eventually we will fly, the wind under our wings.