An Essay on the Principle of Population
I came out of this with a new respect for Malthus. His prediction that agriculture could not improve exponentially, although very wrong, was not really the point of the book. Rather, the point was to discuss how society should deal with the resulting challenge. Further, he was not a doomsayer, but rather a moralist—his main recommendation was that young people marry later, in particular waiting until they are sure they can support children.