If the present examination of some of the subtler forms of matter or of force,(1023) and of their existence in other globes of the solar system than our own, should hereafter lead to a generalization which shall extend natural philosophy as widely beyond its present limits as the discovery made by Newton beyond those of his predecessors, yet these discoveries can have no bearing, favourable or unfavourable to religion, distinct in kind from that of present ones. If even a still mightier stride should be taken, and physiology be able to lay bare the subtle processes through which mind acts on body;(1024) yet the difficulty would only be an enhanced form of that which is already used to discredit the spirituality and immortality of the soul. If we pass from the physical to the moral or metaphysical sciences, there is still less ground for expecting progress. True so far as they go, they offer no opportunity for enlargement, unless perhaps a more careful analysis, by means of the fertile principle of mental association,(1025) should cast light on the sensational source of ideas and the physiological side of mind; and even this would leave the independent evidence of the mental data, moral and intellectual, of religion, on the same basis as at present. Critical science again has attained such perfection, that there is no possibility of an entirely new range of critical thought springing up in reference to religion, such as arose when the German mind was creating the science of historical criticism.