“Certainly one may, with as much reason and decency, plead for murder, robbery, lewdness, and barbarity, as for this practice: They are not more contrary to the natural dictates of Conscience, and feelings of Humanity; nay, they are all comprehended in it.”

Sec. 145
Some Thoughts Concerning Education (1693)
Context: The Indians, whom we call barbarous, observe much more decency and civility in their discourses and conversation, giving one another a fair silent hearing till they have quite done; and then answering them calmly, and without noise or passion. And if it be not so in this civiliz'd part of the world, we must impute it to a neglect in education, which has not yet reform'd this antient piece of barbarity amongst us.

Proposals for a New Law Code (1768), Item 123

Vol. I, p. 188
William Lloyd Garrison 1805-1879 (1885)

To which may be replied,
1770s, African Slavery in America (March 1775)

One Minute News (1947), interview with British Pathé's John Parsons

The Rights of the Colonists (1772)

Pennsylvania Constitution (1776), Declaration of Rights http://www.pahouse.com/pa_const.htm; this may be based upon principles stated by Penn, but earlier renditions in this form have not been located.
Disputed
Context: All men have a natural and indefeasible right to worship Almighty God according to the dictates of their own consciences; no man can of right be compelled to attend, erect, or support any place of worship, or to maintain any ministry against his consent; no human authority can, in any case whatever, control or interfere with the rights of conscience, and no preference shall ever be given by law to any religious establishment or modes of worship.

Sec. 98
Some Thoughts Concerning Education (1693)
Context: He will better comprehend the foundations and measures of decency and justice, and have livelier, and more lasting impressions of what he ought to do, by giving his opinion on cases propos'd, and reasoning with his tutor on fit instances, than by giving a silent, negligent, sleepy audience to his tutor's lectures; and much more than by captious logical disputes, or set declamations of his own, upon any question. The one sets the thoughts upon wit and false colours, and not upon truth; the other teaches fallacy, wrangling, and opiniatry; and they are both of them things that spoil the judgment, and put a man out of the way of right and fair reasoning; and therefore carefully to be avoided by one who would improve himself, and be acceptable to others.