"I have been primarily interested in how and why ordinary people do unusual things, things that seem alien to their natures. Why do good people sometimes act evil? Why do smart people sometimes do dumb or irrational things?"

This quote by Philip Zimbardo speaks to the concept that people are capable of doing things that are out of character for them. He is interested in why people do things that are unusual or seemingly contradictory to their nature. He is asking why individuals who are typically great can in some cases act in an evil way, and why people who are generally smart can in some cases do irrational or dumb things. This quote speaks with the concept that people are intricate and can act in ways that are unforeseen. It also talks to the concept that people are capable of making errors and that it is important to understand why these mistakes happen. Zimbardo's quote is a suggestion that individuals are capable of making errors which it is important to understand why these mistakes occur in order to learn from them.