A common analogy to aging is that of a boulder being worn down to rubble by the unremitting onslaught of time. In contrast, Swaab's "use it or lose it" concept is important because it emphasizes some positive consequences of experience. For example, early exposure to complex experience may offer some protection from "wear and tear" degradation through improvements in vascular support, diet, exercise, and coping with stress. Exposure to complex experience in old age can also generate new synapses in the cerebral cortex and cerebellum. This new perspective is not completely positive, however, because it appears that the senescent breakdown of supporting systems may ultimately constrain the positive benefits of experience in old age. Thus the evidence indicates that the use of environmental therapies should encompass the entire life span to produce successful aging.