Once he overcomes his fear of unknown ,what now urges him to explore his world

Curiosity

"It was bewildering. He was sprawling through solidity. And ever the light grew brighter. Fear urged him to go back, but growth drove him on. Suddenly he found himself at the mouth of the cave. The wall, inside which he had thought himself, as suddenly leaped back before him to an immeasurable distance. The light had become painfully bright. He was dazzled by it. Likewise he was made dizzy by this abrupt and tremendous extension of space. Automatically, his eyes were adjusting themselves to the brightness, focusing themselves to meet the increased distance of objects. At first, the wall had leaped beyond his vision. He now saw it again; but it had taken upon itself a remarkable remoteness. Also, its appearance had changed. It was now a variegated wall, composed of the trees that fringed the stream, the opposing mountain that towered above the trees, and the sky that out-towered the mountain."