A fascinating TED Talk on the importance of our microbiome in shaping our personalities and behavior. Maybe Epicurus was (by chance) onto something when he said "the rational part resides in the chest"! "Chest" here translates θώραξ (thorax) taken as the part of the body covered by a corselet/body armor: chest, abdominal cavity, trunk, midriff. I still think a rational case can be made for Epicurus's idea that the rational mind resided in the thorax with our own terms like "sick to my stomach" "heart-broken" and "I had butterflies in my stomach".
Henry George Liddell, Robert Scott, A Greek-English Lexicon, θώραξ
