earth has solidity, we have observed a thousand and a thousand times; and
when any new instance of this nature is presented, we draw without
hesitation the accustomed inference. The exact similarity of the cases
gives us a perfect assurance of a similar event; and a stronger evidence
is never desired nor sought after. But wherever you depart, in the least,
from the similarity of the cases, you diminish proportionably the
evidence; and may at last bring it to a very weak analogy, which is
confessedly liable to error and uncertainty. After having experienced the
circulation of the blood in human creatures, we make no doubt that it
takes place in TITIUS and MAEVIUS. But from its circulation in frogs and
fishes, it is only a presumption, though a strong one, from analogy, that
it takes place in men and other animals. The analogical reasoning is much
weaker, when we infer the circulation of the sap in vegetables from our
experience that the blood circulates in animals; and those, who hastily
followed that imperfect analogy, are found, by more accurate experiments,
to have been mistaken.

If we see a house, CLEANTHES, we conclude, with the greatest certainty,
that it had an architect or builder; because this is precisely that
species of effect which we have experienced to proceed from that species
of cause. But surely you will not affirm, that the universe bears such a
resemblance to a house, that we can with the same certainty infer a
similar cause, or that the analogy is here entire and perfect. The
dissimilitude is so striking, that the utmost you can here pretend to is
a guess, a conjecture, a presumption concerning a similar cause; and how
that pretension will be received in the world, I leave you to consider.

It would surely be very ill received, replied CLEANTHES; and I should be
deservedly blamed and detested, did I allow, that the proofs of a Deity
amounted to no more than a guess or conjecture. But is the whole