This is one of those books that kind of hurt my brain to read, but I appreciate because it revealed so much to me. It's about invasive species. It addresses such topics as: what makes some species invasive (successful) in new environments and others not? are introduced species actually harmful? what should we do about them- or are they better left alone? Most of the answers that Thompson arrived at actually surprised me. It seems that the furor about invasive species is either based on very little science, or none at all. Turns out it is quite natural for species to move around the planet and end up in different places than the originated in- if you go back not that far in time, anywhere on earth would be unrecognizable to us. So what gives humans the right to decide that a certain collection of plants and animals in one place is the ideal one, to be protected at all costs? In most cases, invasive species are not to blame for the decline of "natives"; looked at more closely it is often the fault of human changes to environments, or other factors altogether. And the cost of attempts to remove or eradicate alien species (almost always unsuccessful in the end) usually outweighs by far the cost of original "damage". While it still disturbs and alarms me to see news of a certain species disappearing, especially when it is the victim of human alterations to the Earth, I feel like I should in some degree accept that this is just the way of things. The world changes. Some things will die, others will arise. Yes, we are making this happen faster than before- but it would still happen regardless... I still like the idea of having a garden comprised of all native plants, but Thompson has overturned my thinking: I will no longer feel so guilty about planting Dutch flowers in my garden.