the actual progress consists in those internal modifications of which this increased knowledge is the expression.  Social progress is supposed to consist in the produce of a greater quantity and variety of the articles required for satisfying men’s wants; in the increasing security of person and property; in widening freedom of action:  whereas, rightly understood, social progress consists in those changes of structure in the social organism which have entailed these consequences.  The current conception is a teleological one.  The phenomena are contemplated solely as bearing on human happiness.  Only those changes are held to constitute progress which directly or indirectly tend to heighten human happiness.  And they are thought to constitute progress simply because they tend to heighten human happiness.  But rightly to understand progress, we must inquire what is the nature of these changes, considered apart from our interests.  Ceasing, for example, to regard the successive geological modifications that have taken place in the Earth, as modifications that have gradually fitted it for the habitation of Man, and as therefore a geological progress, we must seek to determine the character common to the modifications—­the law to which they all conform.  And similarly in every other case.  Leaving out of sight concomitants and beneficial consequences, let us ask what Progress is in itself.

In respect to that progress which individual organisms display in the course of their evolution, this question has been answered by the Germans.  The investigations of Wolff, Goethe, and Von Baer, have established the truth that the series of changes gone through during the development of a seed into a tree, or an ovum into an animal, constitute an advance from homogeneity of structure to heterogeneity of structure.  In its primary stage, every germ consists of a substance that is uniform throughout, both in texture and chemical composition.  The first step is the appearance of a difference between two parts of this substance; or, as the phenomenon is called in physiological language, a differentiation.  Each of these differentiated divisions presently begins itself to exhibit some contrast of parts; and by and by these secondary differentiations become as definite as the original one.  This process is continuously repeated—­is simultaneously going on in all parts of the growing embryo; and by endless such differentiations there is finally produced that complex combination of tissues and organs constituting the adult animal or plant.  This is the history of all organisms whatever.  It is settled beyond dispute that organic progress consists in a change from the homogeneous to the heterogeneous.

Now, we propose in the first place to show, that this law of organic progress is the law of all progress.  Whether it be in the development of the Earth, in the development of Life upon its surface, in the development of Society, of Government, of Manufactures, of Commerce, of Language, Literature, Science, Art, this same evolution of the simple into the complex, through successive differentiations, holds throughout.  From the earliest traceable cosmical changes down to the latest results of civilisation, we shall find that the transformation of the homogeneous into the heterogeneous, is that in which Progress essentially consists.