Abraham Maslow would be 105 years old today. ThisGreat Graphic, fromResilience.org, depicts the hierarchy of needs is he associated. The more securely the basic needs were satisfied, the easier one can attain the higher levels, ultimately leading to self-actualization.
Unlike other psychologists, like Freud for example, who studied unhealthy people and induced what healthy was, Maslow studied people he thought were self-actualized.