Reason and free inquiry are the only effectual agents against error... They are the natural enemies of error, and of error only... If [free enquiry] be restrained now, the present corruptions will be protected, and new ones encouraged.

the field of knolege is the common property of all mankind

We shall all consider ourselves unauthorized to saddle posterity with our debts, and morally bound to pay them ourselves; and consequently within what may be deemed the period of a generation, or the life of the majority.

Nothing can stop the man with the right mental attitude from achieving his goal; nothing on earth can help the man with the wrong mental attitude.

The following [addition to the Bill of Rights] would have pleased me: The people shall not be deprived or abridged of their right to speak, to write, or otherwise to publish anything but false facts affecting injuriously the life, liberty or reputation of others, or affecting the peace of the [United States] with foreign nations.

To the corruptions of Christianity I am indeed opposed; but not to the genuine precepts of Jesus himself.

Neither Pagan nor Mahamedan nor Jew ought to be excluded from the civil rights of the Commonwealth because of his religion. -quoting John Locke's argument.