Twenty-five years ago psychologist Daniel Gottlieb was in a car crash that left him paralyzed from the neck down. Nevertheless, he continued to practice and even to host a family therapy radio program. When his only grandson Sam was diagnosed with autism and PDD (pervasive developmental disorder), the little boy and his "pop" forged a special bond based on love, endurance, and what Gottlieb describes as "being kindred spirits." Gottlieb decided to share the lessons of his own life to prepare Sam for challenges ahead. The following is an excerpt from the book "Letters to Sam: A Grandfather's Lessons on Love, Loss, and the Gifts of Life."

Dear Sam,

After you were born, I worried about your mother. I would call every day and ask her how you were, and every day she would say the same thing: "Sam is perfect." And that made me worry.

Sam, nobody is perfect. Each of us has imperfections that make us different from anyone else. I was afraid that if Debbie went on believing you were perfect, she would be hurt someday when your different-ness, whatever it was, became visible. And I was afraid that you would be hurt too.

That's why I struggled when I first noticed some unusual things that were happening in your development. You were about fourteen months old when I noticed that you weren't yet talking. You didn't seem to be paying attention to us when we talked to you. I thought there was a problem, but I didn't know how to tell your mother. What if I was fretting about problems that didn't exist? If I conveyed my anxiety to Debbie, I knew she would take my concerns seriously. But was that really fair? Why worry her unnecessarily if, in fact, I was just imagining things?

Despite these reservations, I finally did tell your mother about my concerns. Of course, she and your father had both felt something was wrong, but like any parents, they hoped that they were just imagining things and that you would be fine.

At first we thought you might be deaf. I actually hoped that was the problem, because the other possibilities were so frightening: this could be a brain abnormality, mental retardation, or -- autism. We banged pots and pans when you weren't looking, and often you did not turn around. But when we had your hearing tested, we found out it was just fine.

Then there were intelligence tests, behavior assessments, physical exams. Of course, we went to the best professionals we could find. The label they came up with was PDD -- pervasive developmental disorder -- which places you on the autism spectrum. The label alone didn't tell us much, but at least it gave us an explanation for the way you were acting. And though there are many things we do not know about this disorder, there are some things we do know.

Sam, you are adorable. I mean off-the-charts cute. Your smile can melt anybody's heart, and you are most capable of giving and receiving a great deal of love. All of these things will help you in your life. I also know how much you love me and how much you like to sit on my lap and ride with me in my wheelchair. These things will help me in my life! So now we know that you have your own personality, spirit, and soul, and that you improve the lives of those around you.

But we need to know more.

When you were first diagnosed, your parents and I did everything we could to find out about PDD and autism. We learned that this disability inevitably steals something from children. We also learned that PDD would interfere with your ability to be flexible and to pick up social cues, as well as your fine motor dexterity. And we saw that you would have difficulty with too much stimulation. You would need some things in perfect order so that you could feel safe.

Autism has the power to steal opportunities for contact, intimacy, and love. In a strange paradox, if your autism were more severe, the opportunities you lose might hurt you less. But because your autism is not so severe, you may realize that you lack important skills for connecting with other people -- you may be aware you are different, and that awareness may cause you pain. And because you have wonderful parents and family who love you, they will share your pain. Already I see the hurt your parents feel when you behave differently from your playmates.

So why do I tell you this?

Sam, I want you to know that being different is not a problem. It's just being different. But feeling different is a problem. When you feel different, the feeling can actually change the way you see the world.

Do you remember when we went to Disney World? You were too young and excited to notice, but in many ways I was different from the other people. I couldn't go on many of the rides, I got on the bus differently from everyone else, and I couldn't go swimming with you. Most of the time I felt okay about it. After all, I have been living this way for nearly twenty-five years. But some of the time, I felt different. And those times were pretty sad and embarrassing for me.

The first time I went, about ten years earlier, I'd been thrilled to discover how wheelchair-accessible Disney World is. Every bus had a wheelchair lift. The bus driver had to get out to operate the lift, and everyone on the bus had to wait until I was on. But I was so happy to be able to get around to Adventureland and Tomorrowland, those technical details didn't matter.

When I went with you, the buses were exactly the same, but I wasn't quite so thrilled. I was more conscious of people watching and waiting while I got on. The story I told myself at first was that people were impressed with the technology and happy that I could get around with the rest of them. But that story didn't last long, and the next time I rode the bus, I had a new one. I was convinced that all the people waiting for me to board were hot and tired. They just wanted to get on the bus and didn't want to wait. I was getting on their nerves.

Finally, I got frustrated. Why couldn't it just be easier? I didn't want to hold everyone up while the bus driver went through all the lift preparations. I felt very different. And it was painful.

The bus was the same. The quadriplegia was the same. What changed? What changed was what I did with my mind.

Your different-ness and my different-ness are just facts. Sometimes what we do with our minds turns those facts into pain, and sometimes we can just treat them as facts, acknowledging them but not feeling them. But the more you feel your different-ness, the more lonely you will feel.

Sam, you know what? I no longer worry when your mother says you're perfect. Finally I understand what she means. Your body is not perfect. Neither is your brain. You are different from most other people. But when I look in your eyes and see your sweetness, I can only agree with your mother. In some of the most important ways, you already are perfect.

Love, Pop