Occasionally Thoreau has visitors. If they arrive while he's out, they usually leave a walnut leaf or chip as a sign that they've been there. Natch.
Thoreau isn't sad all on his own. He finds Nature a continuous source of friendliness and cheer.
Besides, he finds that he has a kind of split personality, where one side of him is a spectator observing what the other side of him is doing. So, he's not really alone – a little crazy, but not alone.
Our man thinks people are actually more alone in the company of others since, usually, our contact with the people around us is so superficial.
He explains that he is only alone in the sense that a flower or a fly or a bee is alone in a pasture.
There are a couple of neighbors who Thoreau chats with: an old settler of the woods, as well as an old woman who has a nice herb garden.