Conspicuous in the literature of this propaganda is the appeal to standard modern practice in regard to machinery. "Those to whom the care of delicate mechanical apparatus is entrusted," says the New York Commissioner of Health, "do not wait until a breakdown occurs, but inspect and examine the apparatus minutely, at regular intervals, and thus detect the first signs of damage." "This principle of periodic inspection," says the prospectus of the Life Extension Institute, "has for many years been applied to almost every kind of machinery, except the most marvelous and complex of all,--the human body." To find fault with the drawing of this comparison, with the utilization of this analogy, would be foolish. That many persons would be greatly benefited by submitting to these inspections is certain; it is not impossible that they are desirable for most persons. And the analogy of the inspection of machinery serves excellently the purpose of suggesting such desirability. What is objectionable about its use by the Life Extension propagandists is their evident complacent satisfaction with the analogy as complete and conclusive. Yet nothing is more certain than that, even from the strictly medical standpoint, it ignores an essential distinction between the case of the man and the case of the machine. The machine is affected only by the measures that may be taken in consequence of the knowledge arising from the inspection; the man is affected by that knowledge itself. Whether the possible physical harm that may come to a man from having his mind disturbed by solicitude about his health is important or unimportant in comparison with the good that is likely to be done him by the following of the precautions or remedies prescribed, is a question of fact to which the answer varies in every individual case. It may be that in the great majority of cases the harm is insignificant in comparison with the good. However that may be, the question is there, and it is of itself fatal to the conclusiveness of the _argumentum ex machina_. That this is not a captious criticism, that it is based on substantial facts of life, ordinary experience sufficiently attests; but it may not be amiss to point to a conspicuous contemporary phenomenon which throws an interesting light on the matter. The Christian Scientists regard the _ignoring_ of disease as the primary requisite for health and longevity. That the Christian Science doctrine is a sheer absurdity, no one can hold more emphatically than the present writer; but it cannot be denied that in thousands of cases its acceptance has been of physical benefit through its subjective effect upon the believer. Personally, I would not purchase any benefit to my physical life at such sacrifice of my intellectual integrity; I mention the point only by way of accentuating the undisputed fact that the presence or absence of concern about health may have a potent influence on one's bodily welfare.