The history of science (see Krakatoa by Simon Winchester to learn more) and at the time when Percival Lowell's books on the canals of Mars were all the rage (and they still make interesting reading) Wallace was demonstrating scientifically there were no such things as canals or water running freely on the surface. Some (but not most) of his scientific assumptions are incorrect, but that's only because no one had been to Mars yet! This is an astounding little book, a fun read, and I enjoyed it thoroughly. Having said this, we're still undecided about life on Mars, but it's fascinating to watch the debate that took place over a century ago.