I think if you look at any facet of nature in enough detail, you find it fascinating. How could you not? The universe is so full of marvels. Here's an example -- rain, the shape of rain. I was minding my own business, working on my book, looking out the window, and it was raining and I was noticing that the raindrops were falling in that classic round-looking way, and I thought, 'I wonder if raindrops really are round?' So I started researching it a little, and I discovered that raindrops change shape 300 times a second.