In primates, Lilly had discovered6 that the pleasure system—what could be called the brain’s basic ecstatic circuitry—correlated directly with the sexual arousal network. Male monkeys trained to use his device for self-stimulation would choose to orgasm nonstop for sixteen hours, followed by eight hours of deep sleep, after which they would get right back to it. Pleasure, Lilly had discovered, was an endlessly motivating and potentially all-consuming pursuit (at least in males).
