And it is this breadth of inquiry--directed to subjective as well as objective knowledge--which made Bacon so great a benefactor. The defect in Macaulay's criticism is that he makes Bacon interested in mere outward phenomena, or matters of practical utility,--a worldly utilitarian of whom Epicureans may be proud. In reality he soared to the realm of Plato as well as of Aristotle. Take, for instance, his Idola Mentis Humanae, or "Phantoms of the Human Mind," which compose the best-known part of the "Novum Organum." "The Idols of the Tribe" would show the folly of attempting to penetrate further than the limits of the human faculties permit, as also "the liability of the intellect to be warped by the will and affections, and the like." The "Idols of the Den" have reference to "the tendency to notice differences rather than resemblances, or resemblances rather than differences, in the attachment to antiquity or novelty, in the partiality to minute or comprehensive investigations." "The Idols of the Market- Place" have reference to the tendency to confound words with things, which has ever marked controversialists in their learned disputatious. In what he here says about the necessity for accurate definitions, he reminds us of Socrates rather than a modern scientist; this necessity for accuracy applies to metaphysics as much as it does to physics. "The Idols of the Theatre" have reference to perverse laws of demonstration which are the strongholds of error. This school deals in speculations and experiments confined to a narrow compass, like those of the alchemists,--too imperfect to elicit the light which should guide.