It is true that many of these conditions were outcomes of civilization itself, and that for some of them medicine has merely found the antidotes. Yet the fact that medicine has found antidotes shows that medicine has been keeping pace with progress and has invented measures for preventing the Machine from poisoning itself by a sort of auto-intoxication. That the Machine is in danger of disruption by outside and inside forces has been suggested frequently in this book; so that what seems to be indicated as desirable is a series of discoveries and inventions that will prevent it. But, in attempting this, we must not forget that each new discovery or invention adds another part, that safety devices are sometimes so intricate as to increase the danger element rather than lessen or prevent it, and that safety appliances themselves are apt to get out of order, and thus lead to a false sense of security. These reflections force on our attention the fallibility of the human, the necessity for continuous study of all situations as they successively develop, and the solemn fact that progress is not beneficial of itself; for it may be in the wrong direction. One obvious fact that we have always realized, startles each one of us occasionally; the fact that "people do not know what is good for them." The appetites and instincts of undomesticated brutes are said to be much more trustworthy as guides than those of domesticated brutes and human beings. We, by cultivating our imaginations and reasoning powers, and the brutes by being given food and shelter that they themselves do not have to get, seem to have lost a considerable part of the instinctive abilities with which we were originally blessed. With human beings, many objects that most of us aim for are extremely artificial, and some of them are extremely harmful. An illustration is the craving for much food and little physical labor,--a craving that is gratified almost at once by most people suddenly achieving wealth, with consequences that are always deplorable and are frequently distressing. Of course this comes from excessive yielding to our appetites; but the brutes seem to feel no temptation to excessive yielding; an undomesticated brute seems to know when he has had enough. We not only yield, we go further and force our appetites. Possibly this is only an illustration of the fact that our minds have a sort of inertia, comparable to the inertia of physical objects; so that when we move in any direction, we are apt to go too far. That it is a tendency of human nature to go too far in any line of conduct, when once it is entered on, the facts of daily life continually testify. What reformer in public or private life ever knew when to stop; what money maker ever realized that he had enough money and ceased his efforts to get more? A small percentage have, but only a small percentage.