"First, In showing in how to avoid attempting impossibilities. Second, In securing us from important mistakes in attempting what is, in itself possible, by means either inadequate or actually opposed to the end in view. Thirdly, In enabling us to accomplish our ends in the easiest, shortest, most economical, and most effectual manner. Fourth, In inducing us to attempt, and enabling us to accomplish, object which, but for such knowledge, we should never have thought of understanding. On the ways that a knowledge of the order of nature can be of use."