This lecture presents an outline of early historical observations on pulmonary disorders in relation to age, as well as current studies on respiratory-tract defense mechanisms, with particular reference to pneumonia. Special attention is paid to the prevention of pneumococcal pneumonia by means of vaccines. Although much remains to be learned about this vaccine and its efficacy in some segments of the population at high risk from pneumococcal infection, current knowledge regarding its safety and efficacy warrants it more extensive use. Included are interesting notes on Osler's ambivalent attitude toward pneumonia in old age and his stimulating ideas on retirement, patterned after Trollope's writings, which contain an early cost-benefit analysis for events set in 1980.