While it is literally impossible to write a perfect book in the minds of all, you can write the perfect book for yourself at the time you write it (because people change what they like, your views of your work might change). So what is the perfect book for you? For me, it has to portray a sense of conflict in the mind of the MC as well as in the outside world. The MC can't be at peace because the only way he can fix one of his problem is making the other permanent. Yet, the MC finds a way to maybe not fix both problems, but put them to rest... Move on so to speak.