In 1997, the Italian economist Giorgio Nebbia observed that the negative reaction to the "LTG" study came from at least four sources: those who saw the book as a threat to their business or industry; professional economists, who saw "LTG" as an uncredentialed encroachment on their professional ; the Catholic church, which bridled at the suggestion that overpopulation was one of mankind's major problems; finally, the political left, which saw the "LTG" study as a scam by the elites designed to trick workers into believing that a proletarian paradise was a .