Thus, just as animals of many species, including man, are disposed to respond with fear to sudden movement or a marked change in level of sound or light because to do so has a survival value, so are many species, including man, disposed to respond to separation from a potentially caregiving figure and for the same reasons.
John BowlbyBehind the mask of indifference is bottomless misery and behind apparent callousness, despair.
John Bowlby