ABSTRACT
The panorama of psychiatric thought in the modem era can be divided into three successive major trends. The earliest of these encompassed the somatically centered theories of the nineteenth century, in which man was conceptualized essentially as a biological machine. If disturb ances occurred in the behavior of this machine, they were presumed due either to faulty manufacture-a hereditary defect or constitutional weakness-or to some external noxious agent-an injury, germ, or toxin.
