THREE:"It was part of a plot to ruin us both," Bruce said moodily. "I should have been charged with criminal carelessness, which is fatal to a doctor, and you would have been guilty of administering an overdose. That woman, we know who she was, changed the bottles once and would have changed them again, in fact that is why she returned--the Countess."In studying the growth of philosophy as an historical evolution, repetitions and anticipations must necessarily be of frequent occurrence. Ideas meet us at every step which can only be appreciated when we trace out their later developments, or only understood when we refer them back to earlier and half-forgotten modes of thought. The speculative tissue is woven out of filaments so delicate and so complicated that it is almost impossible to say where one begins and the other ends. Even conceptions which seem to have been transmitted without alteration are constantly acquiring a new value according to the connexions into which they enter or the circumstances to which they are applied. But if the method of evolution, with its two great principles of continuity and relativity, substitutes a maze of intricate lines, often returning on themselves, for the straight path along which progress was once supposed to move, we are more than compensated by the new sense of coherence and rationality where illusion and extravagance once seemed to reign supreme. It teaches us that the dreams of a great intellect may be better worth our attention than the waking perceptions of ordinary men. Combining fragments of the old order with rudimentary outlines of the new, they lay open the secret laboratory of spiritual chemistry, and help to bridge over the interval separating the most widely contrasted phases of life and thought. Moreover, when we have once accustomed ourselves to break up past systems of philosophy172 into their component elements, when we see how heterogeneous and ill-cemented were the parts of this and that proud edifice once offered as the only possible shelter against dangers threatening the very existence of civilisationwe shall be prepared for the application of a similar method to contemporary systems of equally ambitious pretensions; distinguishing that which is vital, fruitful, original, and progressive in their ideal synthesis from that which is of merely provisional and temporary value, when it is not the literary resuscitation of a dead past, visionary, retrograde, and mischievously wrong. And we shall also be reminded that the most precious ideas have only been shaped, preserved, and transmitted through association with earthy and perishable ingredients. The function of true criticism is, like Robert Brownings Roman jeweller, to turn on them the proper fiery acid of purifying analysis which dissolves away the inferior metal and leaves behind the gold ring whereby thought and action are inseparably and fruitfully united.