If Smith had confined himself to this issue, his book would have been much more coherent. But, like so many geographers who decide to write books explaining all human history, he ranges so widely and superficially that he ends up saying nothing very much about everything. One moment we are reading about the Nilometers used by the ancient Egyptians to measure river levels, the next we are on to the rise of Chinese communism. As a result, entire sections read like extracts from a child’s encyclopaedia, explaining, say, the origins of the American Civil War or the first Opium War. The Dam Busters’ raid happened on a river, so there are four pages on that. Then there are a couple of pages about Stalingrad that might have come from some dictionary of world battles. “Another example of how rivers influenced the strategies and battle tactics of the Second World War was Operation Market Garden,” the next paragraph begins, ominously.