Every one who has meditated on the subject at all has become aware that the world which we see and hear and feel, the world of sense-perception, is not all that we have to do with. Behind the visible and material world there lies the invisible, the _X_ world, which we cannot weigh and analyze, but the existence and potency of which we are compelled to assume. It is the literal truth to say that no man can take a single step even in the most mundane and practical affairs of life without a belief, implicit or explicit, in the spiritual unity and reality underlying the fleeting panorama of sense-impressions. Nothing else can give him any assurance of the constancy, the orderly inter-relation, of the phenomena with which he has to deal, and with which he could not deal intelligently did not this constancy exist. Now when man begins to be aware that there is something more in the world than is immediately apparent to sense, his thinking on the subject may take several different lines, but it is probable that all of them may be referred to one or other of two main divisions, the Dualistic and the Monistic.[140] The Dualist will regard the world of sense-perception, whether originally produced and organized by the invisible or not, as now more or less independent of the latter, or even hostile to it, and he will generally interpret his own being as something properly belonging to the invisible world but for a time mysteriously and unhappily entangled, through the flesh, with the other. This is Platonic theology, carried by Paul into Christianity, and it eventuates, when driven to its conclusion by a rigorous and inhuman logic, in Asceticism. Instead of the Stoic, ‘Live according to Nature’ (a formula in complete harmony, it may be noted, with the Stoic Pantheism), we get, as the formula for ideal conduct, ‘Deny Nature, think the flesh a burden and a shame, fit yourself for the time when your real self will cast it off as a filthy garment.’ On the other hand the Monistic view represented in ancient Europe by the great Stoic school, and in modern times by names such as those of Spinoza, Hegel, Schopenhauer, Lotze, Walt Whitman, refuses to separate the visible and the invisible worlds. The former _is_ the latter, made partially accessible to our minds. Man is a part of nature, bound up in all his being with the framework of the Universe. The flesh is not a bond on the spirit but an instrument of life, and what we acquire through it is just as valuable and as eternal as anything else. “Objects gross and the unseen soul are one,” says Whitman—the distinction between subject and object, the perceiver and the perceived, as Schopenhauer argues, is but a mode of cognition.