The laws that forbid the carrying of arms...disarm only those who are neither inclined nor determined to commit crimes. Can it be supposed that those who have the courage to violate the most sacred laws of humanity...will respect the less important and arbitrary ones... Such laws make things worse for the assaulted and better for the assailants, they serve rather to encourage than to prevent homicides, for an unarmed man may be attacked with greater confidence than an armed man. Thomas Jefferson, quoted from Enlightenment philosopher Cesare Beccarias On Crimes and Punishment, 1764; translated by Jefferson and copied into his Commonplace Book of great quotations.
Added that to the quote file thanks.