Before entering on our task of reconstruction, we must turn aside to consider with what success the same enterprise has been attempted by modern German criticism, especially by its chief contemporary representative, the last and most distinguished historian of Greek philosophy. The result at which Zeller, following Schleiermacher, arrives is that the great achievement of Socrates was to put forward an adequate idea of knowledge; in other words, to show what true science ought to be, and what, as yet, it had never been, with the addition of a demand that all action should be based on such a scientific knowledge as its only sure foundation.[87] To know a thing was to know its essence, its concept, the assemblage of qualities which together constitute its definition, and make it to be what it is. Former thinkers had also sought for knowledge, but not _as_ knowledge, not with a clear notion of what it was that they really wanted. Socrates, on the other hand, required that men should always be prepared to give a strict account of the end which they had in view, and of the means by which they hoped to gain it. Further, it had been customary to single out for exclusive attention that quality of an object by which the observer happened to be most strongly impressed, passing over all the others; the consequence of which was that the philosophers had taken a one-sided view of facts, with the result of falling into hopeless disagreement among themselves; the Sophists had turned these contradictory points of view against one another, and thus effected their mutual destruction; while the dissolution of objective certainty had led to a corresponding dissolution of moral truth. Socrates accepts the Sophistic scepticism so far as it applies to the existing state of science, but does not push it to the same fatal conclusion; he grants that current beliefs should be thoroughly sifted and, if necessary, discarded, but only that more solid convictions may be substituted for them. Here a place is found for his method of self-examination, and for the self-conscious ignorance attributed to him by Plato. Comparing his notions on particular subjects with his idea of what knowledge in general ought to be, he finds that they do not satisfy it; he knows that he knows nothing. He then has recourse to other men who declare that they possess the knowledge of which he is in search, but their pretended certainty vanishes under the application of his dialectic test. This is the famous Socratic irony. Finally, he attempts to come at real knowledge, that is to say, the construction of definitions, by employing that inductive method with the invention of which he is credited by Aristotle. This method consists in bringing together a number of simple and familiar examples from common experience, generalising from them, and correcting the generalisations by comparison with negative instances. The reasons that led Socrates to