reflection; nor is it in our power to recal the original object, as
often as we have occasion to contemplate it. Ambiguity, by this means,
is gradually introduced into our reasonings: Similar objects are readily
taken to be the same: And the conclusion becomes at last very wide of
the premises.

One may safely, however, affirm, that, if we consider these sciences in
a proper light, their advantages and disadvantages nearly compensate
each other, and reduce both of them to a state of equality. If the mind,
with greater facility, retains the ideas of geometry clear and
determinate, it must carry on a much longer and more intricate chain of
reasoning, and compare ideas much wider of each other, in order to reach
the abstruser truths of that science. And if moral ideas are apt,
without extreme care, to fall into obscurity and confusion, the
inferences are always much shorter in these disquisitions, and the
intermediate steps, which lead to the conclusion, much fewer than in the
sciences which treat of quantity and number. In reality, there is
scarcely a proposition in Euclid so simple, as not to consist of more
parts, than are to be found in any moral reasoning which runs not into
chimera and conceit. Where we trace the principles of the human mind
through a few steps, we may be very well satisfied with our progress;
considering how soon nature throws a bar to all our enquiries concerning
causes, and reduces us to an acknowledgment of our ignorance. The chief
obstacle, therefore, to our improvement in the moral or metaphysical
sciences is the obscurity of the ideas, and ambiguity of the terms. The
principal difficulty in the mathematics is the length of inferences and
compass of thought, requisite to the forming of any conclusion. And,
perhaps, our progress in natural philosophy is chiefly retarded by the
want of proper experiments and phaenomena, which are often discovered by
chance, and cannot always be found, when requisite, even by the most