I haven't read the book but I think I can try to explain how learning about some philosophers has helped me deal with my depression. There are lots of factors that influence my sense of hopelessness. For a long time I would just try to not think about how everyone I love (and myself) would die and humanity was going to eventually destroy itself. And life seemed pretty meaningless. Next I would try to believe what the majority of other people believe. But even if I really tried, I felt like I was forcing myself to think a certain way and I suspected I was just lying to myself. Life just really seemed to rot and it seemed to rot for millions of people on earth. There was no getting around that.

Then I ran across some philosophers that seemed to think the same way I did. What helped me was to see what they did when they reached the same spot I was at. They didn't just stop there, they went on. "OK, so life rots and is meaningless. Now what?"

It seemed that Voltaire thought some of the same things I did about the randomness and unfairness of life. So I could stop trying to conform my thoughts to everyone else's and I could stop trying to just not have the thoughts. Two quotes of his really helped: "Life is a shipwreck, but we must not forget to sing in the lifeboats." and "I have chosen to be happy because it is good for my health." So I got unstuck a little and started to learn more about how to enjoy life even though it rots.

But this helped me because my thoughts had already gotten me stuck. Lots of times people would tell me to just stop thinking too much. But for me that wasn't the answer. It would have helped if someone had said, " Oh yeah, other people have struggled with that, here are some of their thoughts that you might want to look at."

Hope that made a little sense. I'm not saying philosophy would help everyone, but it's really helped me.