Understanding how practitioners may evolve over time can help individuals and organizations to plan for career change and to manage it properly. Since the early 1970s, several life-cycle theories of careers have been developed, partly as a result of psychological examination of adult development. These theories find their roots primarily in the work of Carl Jung and Erik Erikson. Jung wrote a "noon of life" transition from youth to middle life, occurring between the ages of 35 and 40. This noon of life is the "last summons to attain all of one's capabilities." Psychosomatic symptoms at this age and such ailments as depression and ulcers were seen as resulting from the failure to attain goals set during youth.
Erikson suggested that there are eight stages of life, each characterized by the individual's facing and trying to resolve a crisis. He identified the following four adult stages:
1. Adolescence. This is the identity crisis stage. Childhood adaptations are reexamined. The adolescent searches for a new, creative, and independent role through which to contribute to society and derive a sense of meaning and faith.
2. Young adulthood. At this stage there is an intimacy crisis. The individual tries to develop intimacy and sharing with others.
3. Adulthood. Here, the individual faces a generativity crisis. There is concern with others beyond the immediate family. He or she tries to act as a mentor for the next generation.
4. Maturity. At the maturity stage the individual experiences a second identity crisis. There is a sense of near completion. This is a stage of reflection. The individual tries to accept the rightness of his or her life, and of all reality.