The quantity which we eat is partly a matter of habit. There is doubtless a minimum of nourishment which is absolutely necessary for health and strength. On the other hand there is doubtless a maximum limit which cannot be passed without serious injury. Our bodies seem to demand the amount of <p 19> food to which we have accustomed them. If we should increase the amount ten or twenty per cent, we might, for a while, feel some discomfort from it, but soon our system would begin to demand the greater quantity and we could not again return to the lighter diet without a period of discomfort. Likewise the amount of food which most of us consume could be reduced materially with no permanent injury or reduction of energy or danger to health. Following the reduction would be a period of discomfort and probable reduction of weight. This period would last for but a relatively short time, after which we would again strike a physiological equilibrium such that an increase of food would not be craved nor be of any benefit. Any great increase in the amount of physical or mental work results in a feeling of weariness which is usually sufficient to cause us to return to our habitual amount of expenditure of energy. Our system is, however, wonderful in its capacity to adjust itself to changed demands which come upon it, whether these <p 20> demands be in the nature of changes in temperature, in stimulants, in nourishment, or in the expenditure of physical or mental energy. There is, of course, a limit to possible human achievements. There are resources which may not be exhausted without serious injury to health. Those who accomplish most, however, compare favorably with others in length of days and retention of health. _While overwork has its place among the things which reduce energy and shorten life, it is my opinion that overwork is not so dangerous or so common as is ordinarily supposed_. In not a few industries, the dominant house or firm has for its head a man past seventy who still keeps a firm and vigorous grip on the business: men like Richard T. Crane of Chicago, E. C. Simmons of St. Louis, and James J. Hill, whose careers are records of intense industry and absorbed devotion to the work in hand. _Many persons confuse overwork with what is really underwork accompanied with worry or unhygienic practices_. <p 21> A recent writer on sociology calls attention to the fact that nervous prostrations and general breakdowns are most common among those members of society who achieve the least and who may be regarded as parasites. Exercise both of brain and of muscle is necessary for growth and for health.