"It is a new book."
Translation:Es un libro nuevo.
I'm new but that doesn't make sense to me :P lo = 'it' as if I were to say "Yo lo hago" "I do it", and es = is, or in this case "it is". Es already covers the word 'it' in this case. Same reason why el es un libro nuevo wouldn't work. And I don't believe lo would go at the beginning of a sentence.
I'm still pretty new at this, but from what I've seen so far it appears to depend more on whether or not it is an inherent or changeable quality rather than whether or not it is a permanent quality. Something may not be new or young forever, but you can't change the fact that it is right now. Is this an accurate way of looking at it, or just a coincidence in the examples I've seen so far?
For further information on the uses of 'ser' vs. 'estar:
The transitory state rule to distinguish between ser and estar is more a rule of thumb than a fixed law. There are many subtleties. This case can be a little bit confusing and difficult to explain and I don´t want to misguide you but I think in general that if you think of something as an answer to What, you should use es, while if you answer to how, you use está. Again this can be a tricky rule and you have to be careful.