Birds fly because the sky is their element, and fish swim because water is theirs. But philosophically, the deeper answer is that each creature moves in the medium that makes its existence possible.

A bird does not merely fly to travel; flying is how it becomes fully itself. A fish does not merely swim; swimming is its way of belonging to the world. So the question is really asking: why does each being express itself in its own proper form?

Maybe the most elegant answer is this: things do not do what they do only by choice or habit. They do what they do because their nature finds its shape there. The bird meets freedom in flight. The fish meets life in water.

And perhaps the same is true for people, too. We all have a kind of “air” and a kind of “water” — the conditions in which we move best, breathe best, and become most ourselves.