But this multiplicity and complication of facts may merely render the task of the Sociologist extremely difficult, not impossible; and the half truths, and the perplexity of thought above alluded to, may only prove that his scientific task has not yet been accomplished.  Nothing is here presented in the nature of the subject to exclude the strict application of the method.  There is, however, one essential, distinctive attribute of human society which constitutes a difference in the nature of the subject, so as to render impossible the same scientific survey and appreciation of the social phenomena of the world that we may expect to obtain of the physical.  This is the gradual and incessant developement which humanity has displayed, and is still displaying.  Who can tell us that that experience on which a fixed and positive theory of social man is to be formed, is all before us?  From age to age that experience is enlarging.

In all recognized branches of science nature remains the same, and continually repeats herself; she admits of no novelty; and what appears new to us, from our late discovery of it, is as old as the most palpable sequence of facts that, generation after generation, catches the eye of childhood.  The new discovery may disturb our theories, it disturbs not the condition of things.  All is still the same as it ever was.  What we possessed of real knowledge is real knowledge still.  We sit down before a maze of things bewildering enough; but the vast mechanism, notwithstanding all its labyrinthian movements, is constant to itself, and presents always the same problem to the observer.  But in this department of humanity, in this sphere of social existence, the case is otherwise.  The human being, with hand, with intellect, is incessantly at work—­has a progressive movement—­grows from age to age.  He discovers, he invents, he speculates; his own inventions react upon the inventor; his own thoughts, creeds, speculations, become agents in the scene.  Here new facts are actually from time to time starting into existence; new elements are introduced into society, which science could not have foreseen; for if they could have been foreseen, they would already have been there.  A new creed, even a new machine, may confound the wisest of speculations.  Man is, in relation to the science that would survey society, a creator.  In short, that stability in the order of events, that invariable recurrence of the same linked series, on which science depends for its very existence, here, in some measure, fails us.  In such degree, therefore, as humanity can be described as progressive, or developing itself, in such degree is it an untractable subject for the scientific method.  We have but one world, but one humanity before us, but one specimen of this self developing creature, and that perhaps but half grown, but half developed.  How can we know whereabouts we are in our course, and what is coming next?  We want the history of some extinguished world in which a humanity has run its full career; we need to extend our observation to other planets peopled with similar but variously developed inhabitants, in order scientifically to understand such a race as ours.