David Hofld answers the question "Is selling a science or art?" The existing controversy is resolved through statistics and studies that have revealed that the sale is an intertwined science with other sciences such as psychology, economics and other sciences. Hofld does not provide his own experience in the world of sales, such as various other books in the same field, but rather adds to it the results of studies and experiences, explaining that the sale is the results that are subject to change, development and growth,