Thoreau most often creates a philosophical and even whimsical mood. To him, nearly everything holds a lesson to be learned, and that progress is an illusion. In fact, life is an illusion. For example, "the Universe is wider than our views of it,” (Thoreau). Thoreau refutes the idea that 'the cure to sickness is a change of scenery' with the true cure is a change of soul.
In addition, "the mass of men lead lives of quiet desperation," (Thoreau). This implies philosophical ideas, extending into a level further then presented on the front. Thoreau isn't just at Walden to learn about himself. He represents universal ideas, that anyone can hold.
Lastly, Thoreau's mood shines through when he is constantly questioning the meaning of life, what it is to live, and what he lives for. "I went to the wood because I wished to live deliberately, to front the essential facts of life, and see if i could not learn what it had to teach, and not, when I came to die, discover that I had not lived," (Thoreau). This is the main point of the book. Why are we here? What is living? How can I really live? How does one avoid dying without ever experiencing living? The mentioned quote implies all of these questions, going deep down to the core of life.