things; but their nature and their operation on the understanding
never change.

Were a man, whom I know to be honest and opulent, and with whom I live
in intimate friendship, to come into my house, where I am surrounded
with my servants, I rest assured that he is not to stab me before he
leaves it in order to rob me of my silver standish; and I no more
suspect this event than the falling of the house itself, which is new,
and solidly built and founded._--But he may have been seized with a
sudden and unknown frenzy.--_So may a sudden earthquake arise, and shake
and tumble my house about my ears. I shall therefore change the
suppositions. I shall say that I know with certainty that he is not to
put his hand into the fire and hold it there till it be consumed: And
this event, I think I can foretell with the same assurance, as that, if
he throw himself out at the window, and meet with no obstruction, he
will not remain a moment suspended in the air. No suspicion of an
unknown frenzy can give the least possibility to the former event, which
is so contrary to all the known principles of human nature. A man who at
noon leaves his purse full of gold on the pavement at Charing-Cross, may
as well expect that it will fly away like a feather, as that he will
find it untouched an hour after. Above one half of human reasonings
contain inferences of a similar nature, attended with more or less
degrees of certainty proportioned to our experience of the usual conduct
of mankind in such particular situations.

71. I have frequently considered, what could possibly be the reason why
all mankind, though they have ever, without hesitation, acknowledged the
doctrine of necessity in their whole practice and reasoning, have yet
discovered such a reluctance to acknowledge it in words, and have rather
shown a propensity, in all ages, to profess the contrary opinion. The