I am, with respect, &c.

LETTER XII.

Of the small Consequence to be attached to Men's Speculations, and
the Indulgence which should be extended to them.

Permit me, Madam, to felicitate you on the happy change which you say
has taken place in your opinions. Convinced by reasons as simple as
obvious, your mind has become sensible of the futility of those
notions which have for a long time agitated it; and the inefficacy of
those pretended succors which religious men boasted they could
furnish, is now apparent to you. You perceive the evident dangers
which result from a system that serves only to render men enemies to
individual and general happiness. I see with pleasure that reason has
not lost its authority over your mind, and that it is sufficient to
show you the truth that you may embrace it. You may congratulate
yourself on this, which proves the solidity of your judgment. For it
is glorious to give one's self up to reason, and to be the votary of
common sense. Prejudice so arms mankind that the world is full of
people who slight their judgment; nay, who resist the most obvious
pleas of their understanding. Their eyes, long shut to the light of
truth, are unable to bear its rays; but they can endure the
glimmerings of superstition, which plunges them in still darker
obscurity.

I am not, however, astonished at the embarrassment you have hitherto
felt, nor at your cautious examination of my opinions, which are
better understood the more thoroughly they are examined and compared
with those they oppose. It is impossible to annihilate at once
deep-rooted prejudices. The mind of man appears to waver in a void
when those ideas are attacked on which it has long rested. It finds
itself in a new world, wherein all is unknown. Every system of opinion
is but the effect of habit. The mind has as great difficulty to
disengage itself from its custom of thinking, and reflect on new
ideas, as the body has to remain quiescent after it has long been
accustomed to exercise. Should you, for instance, propose to your
friend to leave off snuff, as a practice neither healthful nor
agreeable in company, he will not probably listen to you, or if he
should, it will be with extreme pain that he can bring himself to
renounce a habit long familiarized to him.

It is precisely the same with all our prejudices; those of religion
have the most powerful hold of us. From infancy we have been
familiarized with them; habit has mad