possible are to be admitted is wrong in the abstract; and the injudicious application of it has I think been productive of a great deal of false reasoning. Unquestionably, where there is no appearance of the existence of certain causes, they are to be admitted with caution: we are not fancifully to multiply them ad libitum merely because we are not satisfied with those that do appear, much less are we to multiply them gratuitously, without any reason at all. But where the supposed causes actually exist, where they are known to exist, and have an obvious connection with certain effects, why deprive any of these causes of the real activity which they seem to possess, in order to make some one of them reel and stagger under a weight of consequences which nature never meant to lay upon it? This mistaken notion of simplicity has been the general fault of all system-makers, who are so taken up with some favourite hypothesis or principle, that they make it the sole hinge on which every thing else turns, and forget that there is any other power really at work in the universe; all other causes being either set aside as false and nugatory, or else resolved into that one. There is another principle which has a deep foundation in nature that has also served to strengthen the same feeling; namely, that things never act alone, that almost every effect that can be mentioned is a compound result of a series of causes modifying one another, and that therefore the true cause of anything is seldom to be looked for on the surface, or in the first distinct agent that presents itself. This principle consistently followed up does not however lead to the supposition that the immediate and natural causes of things are nothing, but on the contrary, that the most trifling and remote are something; it proves that the accumulated weight of a long succession of real, efficient causes is generally far greater than that of any one of them separately:
