Throughout human history, we have sought to understand the changes we observe in ourselves and in others with the passage of time. Does this so-called aging process have some purpose, and to what extent can we control what are otherwise inexorable consequences? Although various philosophical traditions have offered different interpretations of the relation between age and time, a more unified concept of human aging may be developing. Ancient philosophical concepts are converging with insights from developmental genetics, molecular biology, and clinical research. This new approach suggests that aging is a continuum of human growth and development, full of potential and highly modifiable by a combination of personal responsibility and appropriate medical care. In providing this care to older adults, skillful physicians use time as a key diagnostic and therapeutic tool to interpret symptoms properly and to place treatment choices in the context of human values that may change with age. We who care for older adults are the doctors of time. Sadly, in our contemporary system of medical care, time is one of the least understood and most poorly used tools. A medical care system that is increasingly oriented toward minimizing the time spent caring for older adults cannot possibly increase the quality of life for the rapidly growing elderly population. With the potential for substantial life extension within our grasp, we must develop attitudes and skills that are more compatible with the value systems of our older patients.