#23 Magician Master and Apprentice by Raymond Feist
This is one of the first series that I started when it first came out in 1982. It has such a traditional start, it reminds me a lot of the Disney movie the Sword in the Stone. Very simple and great for a kid to start into, but it quickly escalates and becomes bigger and more creative as time goes on.
Boys are coming of age in a remote Duchy of the kingdom, and part of that is the annual ceremony where the masters select their apprentices. Boys dream of fighters or other careers, others leave on the sea for a craft, or if you are not chosen by any of the guild masters go about their way.
At the end of the ceremony, Pug is not selected, but then Kulgan the wizard steps in and picks the youth to be his apprentice. He has never selected one before, and partially picks the boy out of pity. His life changes drastically as he tries to study magic, with no success.
Yet, he uses magic in a dramatic and sudden fashion to save the princess of the kingdom, and is rewarded by being made a squire. Then a war breaks out with people with superior magic and from another reality. He is captured by them, and a new life starts to mingle with its old.
Like I mentioned, it starts out overly simple and builds into a deeper and richer story. I like his books, but the first two that are written as one book and split by the publishers in the US to two books are great.