The same principles apply to all machines; and the common sense of mankind appreciates them, even if the machines are of the human type. A captain of a company of soldiers, in all armies and in all times, has been trained to handle a specific human machine; so has the captain of a football team, so has the rector of a church. The training that each person receives gives him such a subconscious sense of the weights and uses of the various parts of the machine, that he handles them almost automatically--and not only automatically but instantly. The captain on the bridge, when an emergency confronts him, gives the appropriate order instantly. Now the word "machine" conveys to the minds of most of us the image of an engine made of metal, the parts of which are moved by some force, such as the expansive force of steam. But machines were in use long before the steam-engine came, and one of the earliest known to man was man himself--the most perfect machine known to him now, and one of the most complicated and misused; for who of us does not know of some human machine of the most excellent type, that has been ruined by the ignorance or negligence of the man to whose care it was committed? A machine is in its essence an aggregation of many parts, so related to each other and to some external influence, that the parts can be made to operate together, to attain some desired end or object. From this point of view, which the author believes to be correct, a baseball team is a machine, so is a political party, so is any organization. Before the days of civilization, machines were few in type; but as civilization progressed, the necessity for organizations of many kinds grew up, and organizations of many kinds appeared. Then the necessity for knowledge of how to operate those organizations brought about certain professions, first that of the military, second that of the priesthood, and later those of the law, medicine, engineering, etc. As time has gone on, the preparation required for these professions, especially the progressive professions, has become increasingly difficult and increasingly demanded; and the members of the professions have become increasingly strict in their requirements of candidates for membership.