PITTSFIELD, MA - Fifteen-year-old Alejandro Caballero has a history of severe trauma and developmental disability. That's the reason he's at Hillcrest Education Center in Pittsfield, but it's also the reason he's autographing copies of a book. Two years ago, Alejandro created a Christmas tree made out of paper. When a woman was visiting him, he donated the tree to her mother who was in a New Jersey hospital, even though he had never even met her.

"It made a great big hit and it impressed everybody in the hospital. It created a lot of interest," said author Margaret Gartland.

Gartland was so touched by this simple act of generosity that she decided to write "The Alejandro Tree."

"I thought this story was there for me and that I should write the story so that all this goodness wasn't lost," said Gartland.

The tree Alejandro donated is made of handprints of other kids, just like him, who have been abused or have severe disabilities.

"The handprints represent all of the kids that are at Hillcrest, that are working together, hand in hand so to speak, with their peers and the staff to try to make their lives better," said Hillcrest Educational Center Development Director Steve Conroy.

The words and illustrations in "The Alejandro Tree" are very simple, but the meaning is profound. That's why bookstores in Massachusetts have been selling out.

"All of a sudden people started coming into the store asking me where the book was. They were interested in the story and I sold out the first day," said Home and Gifts owner Karen Keenan.

And now, people everywhere are reading about a boy who helped explain the meaning of Christmas in such a simple way.

"The kindness of a little boy extends far beyond his circle of friends," said Gartland.

Although it may be difficult for Alejandro to express his feelings, it's simple to hear his message.

"I had fun writing it and doing work with the other kids," said Alejandro.

It's his message of hope and happiness. But most importantly, it's his hand in "The Alejandro Tree."