But at the heart of this universal impermanence there is a soul of reality which the poet discerns amid the fleeting atoms of the stone and the fibre of the growing tree. It is as though we found ourselves in a vast hall, filled to repletion with machinery in every condition of motion, from the slowest and scarcely perceptible movements of the hour hand of a watch up to the incalculable rapidity of a fly-wheel. All is flux, change, consumption of energy, wear and tear of the machinery itself. We know it must run down sometime, we know one day it must all be renewed. But amid all this instability we are well aware that there is a secret source of power, a centre whence a renewal of energy ceaselessly arises. Without its incessant action not one single movement in that vast hall could be obtained. It is the one real thing amidst a world of others which are wearing and wasting away and therefore in a true sense unreal. The secret spring whence the energy is generated may be invisible, but we _know_ it is somewhere, and if any one denied its existence we should not take the trouble to answer him. A faint, halting symbol is this of the eternal and unchanging reality at the heart of the worlds--a dim light whereby to illustrate the most solemn of truths, that always and everywhere, in the lightest as in the greatest movements of nature, in the fragrance of a flower, the iridescence of a crystal, or the fierce energies which shoot up mountains of hydrogen flames hundreds of miles high from the crater of the sun, we have the revelation of "a Power without beginning, without end," [3] permanent while all is in a condition of ceaseless flux and change, living while all around are hastening to their deaths, the one only truly existent Being anywhere, the hidden source of all existence and life. So far, we are justified in saying that we stand on the ground of indisputable fact. It is no mere hypothesis of science, still less a figment of the metaphysician's imagination, or an outpouring of a poet's inspiration, that Permanence is the indispensable postulate of the commonest facts of material existence. We have no explanation to give as to the _method_ of such action as has been described on the part of the invisible and universal Energy, for we cannot even explain the _nexus_ between an act of human volitional energy and the raising of an arm. There are the facts, demonstrable and undeniable, but the _how_ of those facts, no man on this earth knoweth or perhaps ever will know. Well may Browning profess himself content to endure in patience the ignorance which is our lot here, if only at length "thy great creation-thought thou wilt make known to me". The "great creation-thought" cannot be known now. Watson is as sure of it as his spiritual ancestor:-- I trust it not this bounded ken.