The Lost Years of Merlin by T.A. Barron is about Merlin when he was a boy, before he was a prophet, before he was a magician, and before he was King Arthur's advisor. Merlin, as a boy, lived in a small village. He starts to notice that strange things are happening around him. One night some boys burn his house down, the fire leaves him blind. Merlin develops what he calls a "second sight" this sight  enables him to see.
    Then Merlin decides to leave his home. He makes a raft and sails out to sea. When he wakes up he finds himself on a beach. After exploring he finds out that he is on the lost island of Fincara. Fincara is a land that's in between Heaven and Earth. Merlin's story continues in the next 3 books.