Surely there is grandeur in knowing that in the realm of thought, at least, you are without a chain; that you have the right to explore all heights and depth; that there are no walls nor fences, nor prohibited places, nor sacred corners in all the vast expanse of thought.

Crimes were committed to punish crimes, and crimes were committed to prevent crimes. The world has been filled with prisons and dungeons, with chains and whips, with crosses and gibbets, with thumbscrews and racks, with hangmen and heads-men — and yet these frightful means and instrumentalities have committed far more crimes than they have prevented.... Ignorance, filth, and poverty are the missionaries of crime. As long as dishonorable success outranks honest effort — as long as society bows and cringes before the great thieves, there will be little ones enough to fill the jails.

Arguments cannot be answered by personal abuse; there is no logic in slander, and falsehood, in the long run, defeats itself.

Liberty a word without which all other words are vain.

Too much doubt is better than too much credulity.

I have not the slightest confidence in 'spiritual manifestations.'

The intellectual advancement of man depends on how often he can exchange an old superstition for a new truth.