This work later became the basis of his most famous work, which states that humanity is driven by the four basic instincts of hunger, love, vanity, and fear.  
His first works were in the field of economics and attacked bimetallism, such as his A History of American Currency and Lectures on the History of Protection.  He later turned to social theory and attacked the work of Henry George, becoming the leading proponent of social Darwinism of the Gilded Age as exemplified by his What Social Classes Owe to Each Other.  This work later became the basis of his most famous work, which states that humanity is driven by the four basic instincts of hunger, love, vanity, and fear.  FTP, identify this social scientist who coined the term "mores" in his 1906 Folkways.
His first works were in the field of economics and attacked bimetallism, such as his A History of American Currency and Lectures on the History of Protection.  
William Graham Sumner