On Sept. 19, 1738, Benjamin Lay, a hunched-back dwarf, with spindly legs, flowing white beard and excessively large head, strode into Philadelphia Yearly Meeting intent on berating his Quaker brethren for keeping African slaves.

Taking a seat at the front of the meetinghouse, Lay waited a few minutes for the gathering to settle into silent worship before delivering a chilling prophecy. Rising to his feet, Lay, dressed in a great coat and carrying a hollowed-out book containing an animal bladder filled with bright red pokeberry juice, warned that "God will shed the blood of those who enslave their fellow creatures!"

To register the point, the enraged abolitionist threw off his coat to reveal a military uniform and sword.  Then he raised the book above his head and plunged the sword through it.  The pacifist Quakers were horrified not only by the sight of the military garb and sword, but by the "blood" that splattered on their heads and bodies.

Before Lay was forcibly removed from the meetinghouse, he prophesied that those Quaker slaveholders "who failed to heed the prophet's call can expect physical, moral and spiritual death."

Such colorful guerrilla theater designed to shame Quaker slaveholders was a common tactic for the eccentric Lay, who demanded immediate and unconditional emancipation.   But it also carried a heavy price. Lay was scorned and mocked by his contemporaries, disowned by the Society of Friends and forgotten by history.

Today, when conflict — and violence — between white supremacists and anti-fascists over Confederate monuments dominate national headlines and, here in Philadelphia, artists debate what makes a monument, Benjamin Lay reminds us that there are other historic figures deserving of memorials.  But they were purposely rejected by society because they challenged the moral conventions of their time period.

I was introduced to Lay when I was a student at Abington Friends School in the early 1970s.  I learned that the anti-slavery crusade for which Quakers are so well-known evolved over nearly a century's time. That the affluence of many 18th-century Friends depended upon slavery and the slave trade. And that Lay genuinely believed God chose him as a vehicle to abolish slavery within the Society of Friends.

Each Wednesday morning, I attended a meeting for worship in the same meetinghouse where Lay carried out many of his sensationalist protests. One winter's Sunday, for example, the eccentric dwarf stood outside the structure with one bare foot buried deep in a snow drift.  When members of Abington Meeting stopped to express their concern for his health, Lay reprimanded them bitterly for "pretending compassion" for him, but "failing to feel the same for slaves who are half-clad."

I attended classes in a school building across the street from the structure where Lay resided for the last third of his life after relocating from Philadelphia.   Here, in a stone cottage that resembled a cave, he cultivated a garden and fruit trees and spun wool for clothing because he refused to eat food or wear garments procured by slave labor.

Inside, he had a 200-volume library, which he consulted to write "All Slave-Keepers That Keep the Innocent in Bondage, Apostates," one of the very first tracts to demand the abolition of slavery. That stone cottage was also the scene of perhaps the most telling episode of Lay's 28-year anti-slavery crusade.

Lay had a great fondness for children and was a favorite with local youth.  Since he often preached about the wickedness of separating slave families to their parents who turned a deaf ear, the little abolitionist decided to illustrate the point by abducting the child of a slave-owning neighbor.

Toward evening, the mother began looking for her child and stopped to question Lay. Feigning ignorance, he asked, "How do you think an African mother feels when her child is torn from her never to be returned?"  When satisfied by the mother's anguish, Lay released the child.

To be sure, Benjamin Lay was extremely antagonistic toward those who disagreed with his anti-slavery views.  Self-righteous and stubborn to a fault, he refused to retreat in the face of resistance.  As a result, he was ridiculed, heckled and dismissed by others as "mentally deficient."  Had it not been for his wife, Sarah, a respected Quaker minister, Lay probably would've been disowned by Philadelphia Yearly Meeting earlier than Aug. 26, 1737.

At the same time, Lay became a personal hero because of his courage to speak truth to power.  He didn't care whether he offended anyone with his outlandish behavior as long as it furthered the anti-slavery cause. Nor were his efforts in vain.

The week before Lay's death on Feb. 3, 1759, Philadelphia Yearly Meeting made the selling and importation of slaves a cause for disownment among its members.

The act paved the way for more mild-mannered and articulate Friends such as Anthony Benezet and John Woolman to persuade the yearly meeting, in 1776, to outlaw slaveholding itself.

William C. Kashatus is a Quaker historian and writer. Email him at bill@historylive.net