That the same causes, acting under different conditions, produce different and even opposite effects, is a well-known scientific truth. The same heat of summer which causes our foods to decay, promotes the growth of plants in the soil; the same cold of winter which increases the pain of bronchial affections, and cuts short the lives of aged and infirm persons, acts as a stimulant and a source of pleasure to the young and healthy. We need not therefore be surprised, that the same physical conditions and principles of nature, act as causes or conditions both of what we term evil and what we term good. If, also the theory of relativity in physical and mental action is true, that change of impression is a necessary cause or condition of consciousness, and that previous experience of pain increases the perception of pleasure, we possess in that theory, as one of the general ideas of science, a partial basis of morality. All these remarks tend to shew, that in order to obtain a truly scientific view of the nature of man, and of man's position and duties in the Universe, we must avoid the errors caused by uncorrected consciousness. Another great moral effect of the continual discovery of new truth in science, is the gradual production and diffusion of uniformity of belief, first amongst scientific men, and then amongst the mass of mankind. This uniformity of belief is a necessary result of the invariability of fact and law; it does not extend to scientific opinions, hypotheses or theories, because they are not necessarily facts, and may be {141} erroneous. A knowledge of science tends to remove differences of opinion between man and man, because it enables every honest examiner to obtain essentially similar results. Scientific research will gradually disclose what is true and what is untrue in doctrine and empirical rules; and what is true will be retained. A universal religion or a scientific philosophy which is composed of contradictory creeds cannot be wholly true. Science is gradually superseding unreasonable beliefs, and inaugurating a true universal gospel in which all men will eventually think alike in fundamental matters. The continued discovery of new truth must of necessity sooner or later lead mankind to the source of all truth and to universal satisfaction and happiness. It has been frequently stated that science is antagonistic to religion; it is evident however that as science is so conducive to morality, it cannot be opposed to true religion, but only to false or unfounded beliefs. Nothing shews more plainly a weakness of moral confidence and a deficiency of faith in an over-ruling power, than a fear that the pursuit of scientific truth will lead to results injurious to mankind. What we most need to fear is, not that our most cherished doctrinal beliefs may be proved to be mistakes, but that we through deficiency of knowledge may be led to do wrong.