questions I might ask, from the man of science I should receive answers which, though differing in richness of detail, in principal would be invariable.
What is this principle? No matter how much the physicist, the chemist and the meteorologist might add to the chain of events as outlined, it would never be other than a chain of events. Even at the present time it might be lengthened almost indefinitely, and although this might show how much we know, it would also show no less clearly that all our knowledge is of one sort, and that scientific explanations, however many or few links we may have in our chains, never amount to more than the enumeration of the conditions under which the events in nature take place. Under the proper conditions evaporation occurs; when the conditions are right a cloud is formed; and, under the proper circumstances, rain falls. This is the chain; in it one event is the outcome of certain conditions and on its shoulders stands the next event if other conditions no less important have been satisfied.
There is something very instructive about a series of this kind, for study, not only of the conditions under which rain falls, but of the conditions under which anything whatever happens in nature, shows conclusively that all the conditions are equal in importance. We ourselves are such poor democrats, however, and so accustomed to special privileges, so much more interested in some things than in others, so inured to our worship of the exceptional and the peculiar, that when we meet with a situation like this, the language of the street, the habit of a life-time, and the teaching of centuries all unfit us for the task of interpreting nature as she really is. Nature is democratic; that which is the condition of an event is neither more nor less than that event's condition, and when, as is always the case, a group of conditions is the basis of an event, that event is suspended, or another takes its place, unless the tiniest condition has cast its vote in the primaries.
It is the neglect of this truth that leads to many of the difficulties of science, for her most ardent votaries are often bent on bestowing special favors among conditions, and now and again knight them. But knighthood among conditions is as precarious an honor in science, as a seat in the house of lords, for sooner or later the bogus knight falls in joust, and another, himself soon to be vanquished, takes his place. It has happened many times in the history of science, one need but think of the changes in the treatment of disease that first one cause, then another then a third has been assigned the leading role in the drama of causation, but each of these in turn has had his vizor torn off, and has stood exposed as a condition which, masquerading under the armor of special privilege, for a time succeeded in imposing on the public as a real cause. Indeed, no one who has set out on the quest for causes in science, has ever returned with anything else than a knowledge of