A fly can't bird, but a bird can fly.....

As per Tao philosophy, everything has an inner nature, a purpose. The challenge is to identify the inner nature and apply it to our benefit.

This is illustrated by this beautiful story by Chuang-tse...

Hui-tse said to Chuang-tse, "I have a large tree which no carpenter can cut into lumber. Its branches  and trunk are crooked and tough, covered with bumps and depressions. No builder would turn his head to look at it. Your teachings are the same—useless, without value. Therefore, no one pays attention to them."

"As you know," Chuang-tse replied, "a cat is very skilled at capturing its prey. Crouching low, it can leap in any direction, pursuing'whatever it is after. But when its attention is focused on such things, it can be easily caught with a net. On the other hand, a huge yak is not easily caught or overcome. It stands like a stone, or a cloud in the sky. But for all its strength, it cannot catch a mouse.

"You complain that your tree is not valuable as lumber. But you could make use of the shade it provides, rest under its sheltering branches, and stroll beneath it, admiring its character and appearance.

Since it would not be endangered by an axe, what could threaten its existence? It is useless to you only because you want to make it into something else and do not use it in its proper way."

In other words, everything has its own place and function. That applies to people, although many don't seem to realize it, stuck as they are in the wrong job, the wrong marriage, or the wrong house. When you know and respect your own Inner Nature, you know where you belong. You also know where you don't belong.