Spying is often referred to as the second oldest profession (prostitution being the first). In Espionage and Covert Operations: A Global History, Professor Vejas Gabriel Liulevicius traces spying from Biblical mythology up to our current surveillance state. While the twelve-hour audio book skims over or leaves out much of the global history of spying, the book is a good overview for anyone interested in the impact of espionage on history.
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