politicians; since they free men from one restraint upon their passions,
and make the infringement of the laws of society, in one respect, more
easy and secure.

After all, I may, perhaps, agree to your general conclusion in favour of
liberty, though upon different premises from those, on which you
endeavour to found it. I think, that the state ought to tolerate every
principle of philosophy; nor is there an instance, that any government
has suffered in its political interests by such indulgence. There is no
enthusiasm among philosophers; their doctrines are not very alluring to
the people; and no restraint can be put upon their reasonings, but what
must be of dangerous consequence to the sciences, and even to the state,
by paving the way for persecution and oppression in points, where the
generality of mankind are more deeply interested and concerned.

115. But there occurs to me (continued I) with regard to your main
topic, a difficulty, which I shall just propose to you without insisting
on it; lest it lead into reasonings of too nice and delicate a nature.
In a word, I much doubt whether it be possible for a cause to be known
only by its effect (as you have all along supposed) or to be of so
singular and particular a nature as to have no parallel and no
similarity with any other cause or object, that has ever fallen under
our observation. It is only when two _species_ of objects are found to
be constantly conjoined, that we can infer the one from the other; and
were an effect presented, which was entirely singular, and could not be
comprehended under any known _species_, I do not see, that we could form
any conjecture or inference at all concerning its cause. If experience
and observation and analogy be, indeed, the only guides which we can
reasonably follow in inferences of this nature; both the effect and
cause must bear a similarity and resemblance to other effects and