At length he determined upon a work called the _Mystery of Iniquity_, in a brief examination of the practice of the times.

This he published in the year 1780, though the chief judge had threatened him if he should give it to the world, and he circulated it free of expense wherever he believed it would be useful.

The above work was excellent as a composition; the language of it was correct; the style manly and energetic; and it abounded with facts, sentiments, and quotations, which, while, they showed the virtue and talents of the author, rendered it a valuable appeal in behalf of the African cause.
The next public advocate was Benjamin Lay[A], who lived at Abington, at the distance of twelve or fourteen miles from Philadelphia.

Benjamin Lay was known, when in England, to the royal family of that day, into whose private presence he was admitted.

On his return to America, he took an active part in behalf of the oppressed Africans.