Csikszentmihalyi and Beattie studied the life histories of 30 men to illustrate the concept of "life theme." A life theme is defined as an affective and cognitive representation of existential problems which a person wishes to resolve. It becomes the basis for an individual's fundamental interpretation of reality and way of coping with that reality. They then investigated the dimensions and sources of variations in life themes, and their effects on career choice and social mobility. Their conclusion was that life themes are constructed from symbolic structures transmitted through interactions which mediate cultural adaptation. Thus, they are functionally equivalent to cognitive and physiological structures transmitted through genetic inheritance.