1. I don't remember writing that only human can understand.
2. According to your logic, since human can understand his circumstance, that means I can't possibly understand it. So since human can write, that means I can't possibly write.
3. Whatever, I think you should play The Witcher 1&2 when you've time, phanta. The game is epic.
Then again, you're a human. You didn't understand the witcher lore & legacy that well to fully determined whether a witcher can't possibly understand it or not.