"Psychology keeps trying to vindicate human nature. History keeps undermining the effort"

This quote by Mason Cooley suggests that psychology is trying to show that humanity is essentially great, however history keeps negating this concept. This implies that human nature is not as good as psychology would like to believe, and that history has actually revealed us that people can excellent evil. This quote might be interpreted as a caution against idealizing humanity, and a suggestion that we need to understand our capacity for misbehavior. It could likewise be viewed as a call to learn from history, and to make every effort to be better than our predecessors. Ultimately, this quote acts as a tip that we must understand our own potential for both great and bad, and strive to make the best choices.