This statement is in the first chapter of Walden where Thoreau recounts his expenses. He is trying to show that people can live simply and independently with very little expenditure, and he makes this statement to assert that nobody gave him any charity, that he lived frugally, simply, and was totally self-sufficient. He goes through a long and detailed list of his expenses, including on building materials and food, and recounts the amount of vegetables he was able to raise in his garden. He observes sardonically that people send their sons to college to study economic theory, but never stop to think that their sons are frittering away their money. He also criticizes the ornate and superficial nature of much of contemporary architecture, contemplating what has been wasted.