Dogs are great. Bad dogs, if you can really call them that, are perhaps the greatest of them all.

Such short little lives our pets have to spend with us, and they spend most of it waiting for us to come home each day.

A person can learn a lot from a dog, even a loopy one like ours. Marley taught me about living each day with unbridled exuberance and joy, about seizing the moment and following your heart. He taught me to appreciate the simple things-a walk in the woods, a fresh snowfall, a nap in a shaft of winter sunlight. And as he grew old and achy, he taught me about optimism in the face of adversity. Mostly, he taught me about friendship and selflessness and, above all else, unwavering loyalty.

A dog doesn't care if you are rich or poor, educated of illiterate, clever or dull. Give him your heart and he will give you his. It was really quite simple, and yet we humans, so much wiser and more sophisticated, have always had trouble figuring out what really counts and what does not.

A dog has no use for fancy cars or big homes or designer clothes. Status symbols mean nothing to him. A waterlogged stick will do just fine. A dog judges others not by their color or creed or class but by who they are inside. A dog doesn't care if you're rich or poor, educated or illiterate, clever or dull. Give him your heart and he will give you his.

Dogs are a really amazing eye opener for us humans because their lives are compressed into such a short period, so we can see them go from puppyhood to adolescence to strong adulthood and then into their sunset years in 10 to 12 years. It really drives home the point of how finite all our lives are.

In a dog's life, some plaster would fall, some cushions would open, some rugs would shred. Like any relationship, this one had its costs. They were costs we came to accept and balance against the joy and amusement and protection and companionship he gave us.