What is the meaning of life? The purpose of existence? How do we, as humans, find happiness here on Earth? These are the questions so often pondered by philosophers and common men alike. These are the very questions humanistic psychologist Abraham Maslow was striving to answer, when, in the 1940's, he proposed a hierarchy of fundamental human needs, which he laid out in a pyramid form -- the most basic needs at the bottom, the most advanced at the pinnacle.

The pyramid layout is not merely for aesthetics: Each need is dependent on the ones below it. The lowest levels must be achieved before the next level of needs can be addressed.

Deficiency Needs

The bottom four layers of the pyramid are what Maslow calls "deficiency needs," or "D-needs," named because of the fact that the individual does not notice their presence, only when they are lacking.

At the very base lie physiological needs, including the most elementary of human necessities: food, water, oxygen, sleep, and other simple bodily functions.

Next in the hierarchy come safety needs. These consist of bodily, financial, and health security.

After physiological and safety needs are met, humans search out love and belonging needs, including community, friendship, family, and romantic love, as well as sexual intimacy.

The last of the deficiency needs are esteem needs--the needs for recognition, respect, as well as self-esteem. The individual achieves these needs by engaging in intellectual and physical activities that give them a sense of worth and value in the eyes of others.

"Being Needs," or "B-needs," are the prime motivators of behavior beyond basic survival.

Self Actualization is the drive to "be all you can be," to make the most of one's talents and circumstances to accomplish all one can.

Maslow extensively studied high-achieving people he considered self-actualizers to better define the qualities of those who reach their full potential. According to his writings, these people possess several qualities in common:

1. Awareness

• efficient perception of reality
• freshness of appreciation
• peak experiences
• ethical awareness

2. Honesty

• philosophical sense of humor
• social interest
• deep interpersonal relationships
• democratic character structure

3. Freedom

• need for solitude
• autonomous, independent
• creativity, originality
• spontaneous

4. Trust

• problem centered
• acceptance of self, others, nature
• resistance to enculturation - identity with humanity

Self-Transcendence is an additional need that Maslow added to the pyramid after further feedback and research, and encompasses needs relating to the greater human experience, as opposed to the needs of the individual. These needs are sometimes referred to as "spiritual needs," and are considered by many the last step towards the ultimate purpose of human life.