Relations between a dog and a man
It’s the main theme of the novel which is clear for the reader from the very beginning of the plot. The whole story is soaked with the narrator’s/author’s/protagonist’s love to the dog, and the dog’s endless allegiance to his closest creature – the man. John gets attached to Marley from the very moment when he saw him. No matter how many dirty tricks the dog did, John always loved him and treated him, as if he were a member of the family. Only in some time John realized why he had attached to Marley so fast – they were very similar. John even adored Marley in some way: the dog was much braver and vigorous than he himself.
Relations between a wife and husband
This theme is not so clear than the first one, but it’s still not less important. The issue of relations here is deep; it makes the reader rethink his/her family values and priorities. Considering how John and his wife go both through serious problems (the death of their beloved dog) and small issues (food stolen by dog from the children’s table) with enviable cohesion and mutual support and love, the reader sees in these relations a kind of perfect ones.
Family member
When we talk about a family we imagine a mother, father and their children; this image is somehow expanded out in the novel. Here, a dog becomes a member of a happy family, but the other members understand it only when Marley passes away. The message of the author is nothing but a simple state – to appreciate things and people, in the given example it is an animal, when they are alive and are with us. It must be the simplest philosophical idea of all the times.