Locke’s essay impelled him further in the same path of patient and cautious interrogation of experience; for the same method which established gravitation presided over the birth of the experiential psychology. Newton instead of elaborating a system of vortices, or another, out of his own consciousness, industriously and patiently waited on the phenomena. Locke, too, instead of inventing a romance of the soul, to use Voltaire’s phrase, sagaciously set himself to watch the phenomena of thought, and ‘reduced metaphysics to being the experimental physics of the soul.’[34] Malebranche, then the reigning philosopher in France, ‘astonished the reason of those whom he delighted by his style. People trusted him in what they did not understand, because he began by being right in what they did understand; he seduced people by being delightful, as Descartes seduced them by being daring, while Locke was nothing more than sage.’[35] ‘After all,’ Voltaire once wrote, ‘we must admit that anybody who has read Locke, or rather who is his own Locke, must find the Platos mere fine talkers, and nothing more. In point of philosophy, a chapter of Locke or Clarke is, compared with the babble of antiquity, what Newton’s optics are compared with those of Descartes.’[36] It is curious to observe that De Maistre, who thought more meanly of Plato than Voltaire did, and hardly less meanly than he thought of Voltaire himself, cried out that in the study of philosophy contempt for Locke is the beginning of knowledge.[37] Voltaire, on the other hand, is enchanted to hear that his niece reads the great English philosopher, like a good father who sheds tears of joy that his children are turning out well.[38] Augustus published an edict _de coercendo intra fines imperio_, and like him, Locke has fixed the empire of knowledge in order to strengthen it.[39] Locke, he says elsewhere, traced the development of the human reason, as a good anatomist explains the machinery of the human body: instead of defining all at once what we do not understand, he examines by degrees what we want to understand: he sometimes has the courage to speak positively, but sometimes also he has the courage to doubt.[40] This is a perfectly appreciative account. Locke perceived the hopelessness of defining things as they are in themselves, and the necessity before all else of understanding the reach of the human intelligence; the impossibility of attaining knowledge absolute and transcendent; and the limitations of our thinking and knowing faculties within the bounds of an experience that must always be relative. The doubt which Voltaire praised in Locke had nothing to do with that shivering mood which receives overmuch poetic praise in our day, as the honest doubt that has more faith than half your creeds. There was no question of the sentimental juvenilities of children crying for light. It was by no means religious doubt, but philosophic; and it