Nietzsche, reflecting the physiological assumptions of his era, conceived of the mind in “energetic” terms, treating emotions as dynamic forces that build up and require discharge or sublimation—a view later formalized in Freud’s hydraulic model of the drives. The Stoic philosophers, by contrast, advanced a cognitive theory of emotion, defining each passion as a judgment or evaluative belief. This Stoic perspective was the original philosophical inspiration of modern cognitive-behavioural therapy (CBT), whose empirical success in emotional disorders can be seen as a vindication of the cognitive model over the older hydraulic or psychodynamic notion. Who was right?