A dog reflects the family life. Whoever saw a frisky dog in a gloomy family, or a sad dog in a happy one? Snarling people have snarling dogs, dangerous people have dangerous ones.
When they took a young man into Tellson's London house, they hid him somewhere till he was old. They kept him in a dark place, like a cheese, until he had the full Tellson flavour and blue-mould upon him. Then only was he permitted to be seen, spectacularly poring over large books, and casting his breeches and gaiters into the general weight of the establishment.
Your next-door neighbor is not a man; he is an environment. He is the barking of a dog; he is the noise of a piano; he is a dispute about a party wall; he is drains that are worse than yours, or roses that are better than yours.