This chapter discusses physiology of emotions, where primary emotions are innate, such as the fear of large size. Secondary emotions are acquired later, such as any stimulus which generates symptoms similar to those induced by primary emotions leads to an emotional experience because the brain has learnt to associate those symptoms with either aversive or pleasant stimuli. The emotional significance of a sensory stimulus is evaluated both at conscious and unconscious level. The significance of unconscious evaluation, which is a primitive mechanism, is to elicit quick responses which would minimise the harmful effects of an unpleasant or dangerous stimulus. One category of responses is the autonomic and neuroendocrine responses which improve the ability of the organism to face a stressful situation. Feelings originate through two broad mechanisms, such as indirectly via visceral effects, and directly through changes in neurochemistry of the brain. Mind influences the body in a profound manner through neuroendocrine mechanisms.