The birds got even heavier and fatter and could not escape from the cages. But one bird refused to eat anything and got thinner, eventually escaping through the bars of the cage. You cannot escape. If you are attached to your self and to enjoyment of the physical body, you will be enslaved by your self-centeredness. If you have no attachment to self, then you will be like empty space or like the sky, free and at ease, with no obstructions.
Space has enormous capacity.
It can contain everything. Our mental scope, on the other hand, is usually very narrow because we are attached to a self. If we put aside our attachment to a self, our mental scope will be as extensive as space. We are also attached to things in our environment. Some things and situations please us and some are not to our liking.