At the beginning of the technical treatise De Architectura of Vitruvius we can read a very interesting ethnographical excursus and we can pick out Posidonius of Apamea as main source (see De arch. VI 1, 1-10 = FgrHist.87 FF. 120-122), with a clear cross-reference to the qualitative polarity derived from aristothelical thought, that followed Hippocrathes, courage-stupidity / cowardice-sharp mind, enclosed in climatic limits north and south.
Aristotheles dealt with the features of blood in relation with the animal psychology and Posidonius was the first scholar to connect the structure of the human body with the environment conditions, in which he lives, like Hippocrates has already said. Vitruvius uses Greek thought and in particular the posidonian theory of thymos, original part of northern people and site of instincts and emotions. Finally Vitruvius shows to know deeply the Greek debate about ethnographical topics and he is able to propose it to the Roman readers.