An excellent book I recommend. One of my favorite movies 'Adaptation' is sort of based on this book.
One theme of both the book and movie, is how and why people develop deep passions for things in general and orchids in particular. Part of why she, the author, is interested in this is because she feels she has no deep passions but would like to.
Here are two passages from the book on this theme which I really enjoyed:
"Besides, I think the real reason (people are passionate about collecting orchids) is that life has no meaning. I mean, no obvious meaning. You wake up, you go to work, you do stuff. I think everybody's always looking for something a little unusual that can preoccupy them and help pass the time"
The world is so huge that people are always getting lost in it. There are too many ideas and things and people, too many directions to go. I was starting to believe that the reason it matters to care passionately about something is that it whittles the worlds down to a more manageable size. It makes the worlds seem not huge and empty but full of possibility.