The historical or genetic method is the method of Science in general, but considered and employed under a limited aspect. And under its more comprehensive aspect it may be called--though no name is unimpeachable--the method of development. Now the essence of the idea of development--as was clearly shown by Leibniz--is the refusal to admit external interference, and the resolve to let a thing explain itself by itself. It does not, like the mechanical method, manipulate the thing from outside--try to add it up out of factors or items fashioned and fabricated after some external standard. Nor does it, like the chemical, look at the result as an inexplicable alteration, due apparently to a mere stroke of combination or disintegration--yet not obviously reducible to a mere equivalent of its elements. On the contrary, it recognises in the object a certain independence or originality, yet also the presence of an immanent law which does not wait for the outsider to put it together, but constructs itself, as it were, after a plan of its own. There is in the so-called object, though we do not at first sight recognise it, the same originative principle both analytic and synthetic, as we own in thought. The object is--in a true logic--a process, a self-completing process, and not merely an object, mechanical, or other object. It changes, grows or decays, while we observe, unless for brief instants we cut it off from its connexions and arrest its development. And our observation, if truly scientific, must be sympathetic with its process of change. It is neither a mere thing to be explained and construed _ab extra_: nor a mystery of sudden transformation to be passively accepted; but a growth, a history, to be sympathetically watched and understood,--understood, because it follows the same order as the movement of our own thought in the process of knowledge. _Similia similibus cognoscuntur_[6].
One sometimes hears it asked by paradoxical critics at which end a history should begin. And to ordinary dogmatic recklessness, paradoxical the question may well seem. Begin at the beginning, no doubt, is the vulgar reply; which in this case is understood to mean from the earliest point in date (that, of course, being easily ascertained, and a thing known to all men). But,--so Plato long ago well raised the difficulty which will always confront us,--are we to go from the beginnings, or towards the beginnings? And it does not quite solve the question to say that we are to begin with what is known: for under that word the same difficulty re-appears. Can you really know one end without the other? To the vulgar partisan of historical method, its precept means Go to the earlier, if you wish to understand the meaning, the value, and the elements constitutive of the later and subsequent. Begin with origins, with the earliest elements, the phases that first appear; and thus you will get light to see the later as they really stand. That this is a common interpretation of the historical method is notorious. To explain _Homo sapiens_, one is told to study the ape,--the nearest analogue of his lost or missing progenitor: to understand the contemporary horse, go to eohippus, or hipparion, or however his early prototype may be at present named and recognised. And in all this there is a truth--or least a half-truth. But let us equally recognise the other half of the truth. If past throws light on present, present throws not less light on past. You propose, let us say, to write a history of Greece. A wordy philosophy, wise in its own conceit and in fine phrases, will advise you to approach the subject without prepossession or prejudice. So far, good. But what is meant by the absence of prepossession or prejudice? Not a blank openness to impression, not a mere passivity; but if passivity at all, a wise passivity: if openness, the openness of the trained judge.