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.