The closest thing Voltaire said to it was
'Think for yourselves and let others enjoy the privilege to do so too'
(
Prequal This is serious business. Very serious.,
Wed 21 Oct 2009, 17:16,
archived)
That and
"Man who goes to bed with itchy bum wakes up with smelly finger".
Wait - no, that wasn't him.
(
Michael Ellis contributes nothing,
Wed 21 Oct 2009, 17:18,
archived)