Context: William inherited very large possessions, part of which consisted of crown debts, due to the vice-admiral for sums he had advanced for the sea-service. No moneys were at that time less secure than those owing from the king. Penn was obliged to go, more than once, and "thee" and "thou" Charles and his ministers, to recover the debt; and at last, instead of specie, the government invested him with the right and sovereignty of a province of America, to the south of Maryland. Thus was a Quaker raised to sovereign power.
He set sail for his new dominions with two ships filled with Quakers, who followed his fortune. The country was then named by them Pennsylvania, from William Penn; and he founded Philadelphia, which is now a very flourishing city. His first care was to make an alliance with his American neighbors; and this is the only treaty between those people and the Christians that was not ratified by an oath, and that was never infringed. The new sovereign also enacted several wise and wholesome laws for his colony, which have remained invariably the same to this day. The chief is, to ill-treat no person on account of religion, and to consider as brethren all those who believe in one God. He had no sooner settled his government than several American merchants came and peopled this colony. The natives of the country, instead of flying into the woods, cultivated by degrees a friendship with the peaceable Quakers. They loved these new strangers as much as they disliked the other Christians, who had conquered and ravaged America. In a little time these savages, as they are called, delighted with their new neighbors, flocked in crowds to Penn, to offer themselves as his vassals. It was an uncommon thing to behold a sovereign "thee'd" and "thou'd" by his subjects, and addressed by them with their hats on; and no less singular for a government to be without one priest in it; a people without arms, either for offence or preservation; a body of citizens without any distinctions but those of public employments; and for neighbors to live together free from envy or jealousy. In a word, William Penn might, with reason, boast of having brought down upon earth the Golden Age, which in all probability, never had any real existence but in his dominions.
No oaths, no seals, no official mummeries were used; the treaty was ratified on both sides with a yea, yea — the only one, says Voltaire, that the world has known, never sworn to and never broken.
As quoted in William Penn : An Historical Biography (1851) by William Hepworth Dixon
William Penn began by making a league with the Americans, his neighbors. It is the only one between those natives and the Christians which was never sworn to, and the only one that was never broken.
As quoted in American Pioneers (1905), by William Augustus Mowry and Blanche Swett Mowry, p. 80
It was the only treaty made by the settlers with the Indians that was never sworn to, and the only one that was never broken.
As quoted in A History of the American Peace Movement (2008) by Charles F. Howlett, and Robbie Lieberman, p. 33