What is this light ?

A dog that had been born during the deluge was spotted the other day lazing in the compound of the company. Now since he was born when there was only water around and no sunshine, he had no way of knowing what the sun was. So while lazing around in the middle, the sun came out for a while and the sunbeams were on the dog. The dog looked up and wondered whats this bright light. From where has it come.

Refer to a previous post where its been said, and truly so, that for light to exist there must be darkness.