The knowledge of the therapeutic potentials of medicinal plants as well as animal and mineral derivatives can be traced in the remote past of ancient Greek civilization. This primarily empirical knowledge prevails in the folk or traditional medicine until the time of Hippocrates, when it obtains theoretical grounds and thus reshaped it is incorporated in “scientific medicine”. In the works of Dioscorides and Galen the knowledge of ancient drugs and therapeutic substances is systematized and thereafter widely spread. According to the scientific views prevailing in their time, medicines act curatively due to the variety of their “powers” that restores the “equilibrium” of the humors and qualities of the body. The therapy with medicines was combined with diaita, the regulation of the way of living, which, at least in the Hippocratic medicine, constituted the major means of both disease prevention and healing. These therapeutic views and approaches have greatly influenced Western medicine, even that of modern times.