The great Sigmund Freud's profound influence continues, if only backstage. Today, apart from the occasional strict Freudian, the work of his followers, especially Jung, Adler, and Erikson more immediately inform psychodynamic therapy.

Everybody (you, me, the waitress at Denny's) knows that libido (sexual energy) is at the center of Freudian theory of human growth and development. Additionally, there are the personality structures that have long been part of popular parlance: the id (seeking immediate gratification, and acting out the pleasure principal), the ego (the thinking self, regulating the id), and the superego (conscience and ideal self and standards). Individual response to the dynamic tension between eros (life force) and thanatos (death, or destructive force) informs personality.

Freud's stage theory of human development proposes basic personality formation by about age 5. Each of the following stages has its own developmental causes and effects:

1. Oral (birth to about age 2)
2. Anal (ages 2 to 3)
3. Phallic (ages 3 to 6)
4. Latency (approximately ages 6 to puberty)
5. Genital (puberty to old age)