WOLFGANG AMADEUS MOZART has been hanging around Goshen lately. And, as long-dead historically significant figures go, he's in good company. Ever since Mary Pope Osborne moved to town seven years ago, William Shakespeare has decamped here, along with an assortment of Civil War heroes, deep-sea adventurers, vikings, dragon-slayers and Olympic athletes.

They are apparitions, sure -- visitors who come to inform the ''Magic Tree House'' books, which Ms. Osborne has been writing for Random House since 1992 -- but sometimes they become more than that.

''The book I love most is the Shakespeare one,'' Ms. Osborne said while sipping tea recently at the woodsy, treehouse-like home that she and her husband, Will Osborne, an actor, built three years ago, nestled among stately old trees on the edge of Woodridge Lake. She was referring to ''Magic Tree House #25: Stage Fright on a Summer Night,'' published in 2003.

''By the end of that book, I felt I had a private relationship with William Shakespeare,'' she said. ''I went to the Globe. l got really close to that reality. And already I can tell that's the way it's going to feel when I finish this book on Mozart.''

Millions of 6- to 10-year-olds are devoted to Ms. Osborne's books, which revolve around Jack...