We must not attempt to fly, when we can scarcely pretend to creep. In considering any complex matter, we ought to examine every distinct ingredient in the composition, one by one; and reduce everything to the utmost simplicity; since the condition of our nature binds us to a strict law and vary narrow limits. We ought afterwards to re-examine the principles by the effect of the composition, as well as the composition by that of the principles. We ought to compare our subject with things of a similar nature, and even with things of a contrary nature; for discoveries may be, and often are, made by the contrast, which would escape us on the single view. The greater number of the comparisons we make, the more general and the more certain our knowledge is likely to prove, as built upon a more extensive and perfect induction.