"I am by no means speaking of those purely arbitrary systems which we are able at a glance to detect as chimeras that are being pretended to us as realities, but I refer to the methods whereby people have set themselves seriously to study nature. Even the experimental method itself has been more fertile of error than of truth, for though it is indeed the surest, yet is it no surer than the hand of him who uses it. No matter how little we incline out of the straight path, we soon find ourselves wandering in a sterile wilderness, where we can see but a few obscure objects scattered sparsely; nevertheless we do violence to these facts and to ourselves, and resemble them together on a conceit of analogies and common properties amongst them. Then, passing and repassing complaisantly over the tortuous path which we have ourselves beaten, we deem the road a worn one, and though it leads no whither, the world follows it, adopts it, and accepts its supposed consequences as first principles. I could show this by laying bare the origin of that which goes by the name of 'principle' in all the sciences, whether abstract or natural. In the case of the former, the basis of principle is abstraction--that is to say, one or more suppositions: in that of the second, principles are but the consequences, better or worse, of the methods which may have been followed. And to speak here of anatomy only, did not he who first surmounted his natural repugnance and set himself to work to open a human body--did he not believe that through going all over it, dissecting it, dividing it into all its parts, he would soon learn its structure, mechanism, and functions? But he found the task greater than he had expected, and renouncing such pretensions, was fain to content himself with a method--not for seeing and judging, but for seeing after an orderly fashion. This method ... is still the sole business of our ablest anatomists, but it is not science. It is the road which should lead scienceward, and might perhaps have reached science itself, if instead of walking ever on a single narrow path men had set the anatomy of man and that of animals face to face with one another. For, what real knowledge can be drawn from an isolated pursuit? Is not the foundation of all science seen to consist in the comparison which the human mind can draw between different objects in the matter of their resemblances and differences--of their analogous or conflicting properties, and of all the relations in which they stand to one another? The absolute, if it exist at all, is but of the concurrence of man's own knowledge; we judge and can judge of things only by their bearings one upon another; hence whenever a method limits us to only a single subject, whenever we consider it in its solitude and without regard to its resemblances or to its differences from other objects, we can attain to no real knowledge, nor yet, much less, reach any general principle.