"I had three seats in my house; one for solitude, two for companionship, and three for society," Thoreau says of the little hut he constructed with his own hands. When visitors arrived in great and unexpected numbers, there was only one chair for them all, so everyone stood up to save space. Thoreau wrote a lot about being comfortable when sitting down, so it's likely that all the chairs were soft and easy to sit in. He also discussed the importance of having adequate seating inside your house. Without mentioning any specific diseases or ailments, he just said that people need to be able to sit comfortably inside your home so they aren't forced to stay outside even if it is cold or hot outside. So, to summarize, Thoreau had three seats in his house for solitude, conversation, and entertainment. Since most homes today don't have as many rooms as Thoreau's, we need multiple chairs inside our houses for those same reasons.