Locke did his work well: how well is attested by the excitement it caused in the intellectual world, the impulse it gave to speculation in England and on the continent of Europe, the controversies over the author's opinions, the struggle of opposing schools to secure for their doctrines his authority, the appreciation on one side, the depreciation on the other, the disposition of one period to exalt him as the greatest discoverer in the philosophic realm, and the disposition of another period to challenge his title to the name of philosopher. The "Essay" is a small book, written in a homely, business-like style, without affectation of depth or pretence of learning, but it is charged with original mental force. Exhaustive it was not; exhaustive it could not have been. The England of the seventeenth century was not favorable to original researches in that field. The "Essay" was planned in 1670, completed after considerable interruptions in 1687, and published in 1690. To one acquainted with the phases through which England was passing at that period, these dates will tell of untoward influences that might account for graver deficiencies than characterize Locke's work. The scholastic philosophy, from which Locke broke contemptuously away at Oxford, seems to have left no mark on his mind; but the contemptuous revulsion, and the naked self-reliance in which the sagacious but not generously cultivated man found refuge, probably roughened his speculative sensibility, and made it impossible for him to handle with perfect nicety the more delicate facts of his science. It can hardly be claimed that Locke was endowed by nature with philosophical genius of the highest order. While at Oxford he abandoned philosophy, in disgust, for medicine, and distinguished himself there by judgment and penetration. Subsequently his attention was turned to politics, another pursuit even less congenial with introspective genius. These may not be the reasons for the "incompleteness" which so glowing a eulogist as Mr. George H. Lewes admits in the "Essay;" but at all events, whatever the reasons may have been, the incompleteness was felt; the debate over the author's meaning was an open proclamation of it; at the close of a century it was apparent to at least one mind that Locke's attempt must be repeated, and his work done over again more carefully.