himself; of those wants and exigencies which if unsatisfied or insatiable must leave his nature not merely negatively imperfect and finite, but positively defective and as inexplicable as a lock without a key--not necessarily, of needs felt at all times by every man, but of those which manifest themselves naturally and regularly at certain stages of moral and social development; just as the bodily appetites assert themselves under certain conditions not always given. Now there is one form in which this argument from adaptability is somewhat too hastily applied and which it is well to guard against. Were we to find a key accommodated to the wards of a most complicated lock, we should be justified in concluding, with a certainty proportioned to the complexity of the lock, that both originated with one and the same mind; and so, it is urged, if a religion, say Christianity, answers to the needs of human nature, we may conclude that it is from the Author of human nature with a certainty increasing as it is seen to answer to the higher and more complex developments of the soul. Now if, like the key in our illustration, the religion in question were something given _in rerum natura_ independent of human origination in any form, this argument would be practically irresistible. That besides those beliefs which lead man on to an ever fuller understanding of his better self, and stimulate and direct his moral progress, Christianity imposes others more principal, of which man as yet has no exigency, and which hint at some future order of existence that new faculties will disclose--all this, in no wise makes the argument inapplicable. The whole system of beliefs is accepted for the sake, and on the credit, of that part which so admirably unlocks the soul to her own gaze. "Now are we the sons of God, but it doth not yet appear what we shall be;" if besides satisfying our present ideal of religion, Christianity hints at and prepares us for such a transition as that from merely organic to sensitive life, or from this, to rational life, it rather adds to than detracts from the force of the argument.