Pain and pleasure
Some philosophers, such as Jeremy Bentham, Baruch Spinoza, and Descartes, have hypothesized that the feelings of pain (or suffering) and pleasure are part of a continuum. == Perception of pain == === Sensory input system === From a stimulus-response perspective, the perception of physical pain starts with the nociceptors, a type of physiological receptor that transmits neural signals to the brain when activated.