Sense, and Reasoning ("discursus"), the sources of our other ideas. They are to be found in every man, and universal consent is the main criterion by which they are to be discriminated. In fact, there can be no doubt that the dogma of Innate Ideas and Innate Principles, in the form attacked by Locke, was a natural, if not the legitimate, interpretation of much of the philosophical teaching of the time, and that it was probably the form in which that teaching was popularly understood. It lay, moreover, as Locke's phrase is, along the "common road," which was travelled by the majority of men who cared about speculative subjects at all, and from which it was novel, and therefore dangerous, to diverge. The most effective, perhaps, of Locke's arguments against this doctrine is his challenge to the advocates of Innate Principles to produce them, and show what and how many they are. Did men find such innate propositions stamped on their minds, nothing could be more easy than this. "There could be no more doubt about their number than there is about the number of our fingers; and 'tis like, then, every system would be ready to give them us by tale." Now "'tis enough to make one suspect that the supposition of such innate principles is but an opinion taken up at random; since those who talk so confidently of them are so sparing to tell us which they are." (Bk. I., ch. iii., § 14.) The great majority, indeed, of those who maintain the existence of innate principles and ideas attempt no enumeration of them. Those who do attempt such an enumeration differ in the lists which they draw up, and, moreover, as Locke shows in the case of the five practical principles of Lord Herbert of Cherbury, give no sufficient reason why many other propositions, which they regard as secondary and derived, should not be admitted to the same rank with the so-called innate principles, which they assume to be primary and independent. Locke is here treading on safer ground than in many of his other criticisms. The fact is that it is impossible clearly to discriminate between those propositions which are axiomatic and those which are derived--or, in the language of the theory which Locke is combating, between those which are innate and those which are adventitious. Race, temperament, mental capacity, habit, education, produce such differences between man and man that a proposition which to one man appears self-evident and unquestionable will by another be admitted only after considerable hesitation, while a third will regard it as doubtful, or even false. Especially is this the case, as Locke does not fail to point out, with many of the principles of religion and morals, which have now been received by so constant a tradition in most civilized nations that they have come to be regarded as independent of reason, and, if not "ingraven on the mind" from its birth, at least exempt from discussion and criticism. The circumstance, however, that they are not universally