With the illuminating principle of evolution came a new and generously rich conception of human growth and development.  The panorama of evolution carried man back far beyond the limits of recorded human history and indicated an origin as lowly as the succeeding uplift has been sublime.  The old depressing and fatalistic notion that the human race was on the downward path, and that the march of civilization must sooner or later end in a cul-de-sac (a view which found frequent expression in the French writers of the eighteenth century and which dominated the skepticism of the dark hours preceding the Revolution)—­this fatalistic view met its death-blow in the principle of evolution.  A vista of hope entirely undreamed of stretched out before the race.  If the tremendous leverage of the untold millenniums of brute and savage ancestry could be overcome, even in slight measure, by a few short centuries of intelligence and reason, what might not happen in a few more centuries of constantly increasing light?  In short, the principle of evolution supplied the perspective that was necessary to an adequate evaluation of human progress.

But this inspiriting outlook which was perhaps the most comprehensive result of Darwin’s work had indirect consequences that were vitally significant to education.  It is with mental and not with physical development that education is primarily concerned, and yet mental development is now known to depend fundamentally upon physical forces.  The same decade that witnessed the publication of the Origin of Species also witnessed the birth of another great book, little known except to the specialist, and yet destined to achieve immortality.  This book is the Elements of Psychophysics, the work of the German scientist Fechner.  The intimate relation between mental life and physical and physiological forces was here first clearly demonstrated, and the way was open for a science of psychology which should cast aside the old and threadbare raiment of mystery and speculation and metaphysic, and stand forth naked and unashamed.

But all this was only preparatory to the epoch-making discoveries that have had so much to do with our present attitude toward education.  The Darwinian hypothesis led to violent controversy, not only between the opponents and supporters of the theory, but also among the various camps of the evolutionists themselves.  Among these controversies was that which concerned itself with the inheritance of acquired characteristics, and the outcome of that conflict has a direct significance to present educational theory.  The principle, now almost conclusively established,[5] that the characteristics acquired by an organism during its lifetime are not transmitted by physical heredity to its offspring, must certainly stand as the basic principle of education; for everything that we identify as human as contrasted with that which is brutal must look to education for its preservation and support.  It has been stated