Heart *and* brain. The current consensus in neurology is that the brain is as much a feeling organism as a thinking one, and that cognition itself is inextricably linked to emotion. I recommend Antonio Damasio’s book Descartes’ Error: Emotion, Reason, and the Human Brain (O’Neill Library QP401 .D2 1994) as an early & influential title. There’s also been a lot of research into the effects of gut microbiota on mood, depression, and anxiety (bit.ly/gut-mood). Gut feeling? It’s truer than we knew, and bacteria may even play a part. Heart, brain, gut… all of it and more: neurons extend throughout your entire body, sort of like all the network cables in a Wall.