On the Sublime and Beautiful/Part I/Chapter 6
MOST of the ideas which are capable of making a powerful impression on the mind, whether simply of Pain or Pleasure, or of the modifications of those, may be reduced very nearly to these two heads, self-preservation and society; to the ends of one or the other of which all our passions are calculated to answer. The passions which concern self-preservation, turn mostly on pain or danger. The ideas of pain, sickness, and death, fill the mind with strong emotions of horror; but life and health, though they put us in a capacity of being affected with pleasure, make no such impression by the simple enjoyment. The passions therefore which are conversant about the preservation of the individual turn chiefly on pain and danger, and they are the most powerful of all the passions.