By submitting pamphlets and petitions, Cooper appealed to and encouraged George Washington and the Congress to make efforts to abolish slavery.

He is noted for writing a 22-page anti-slavery tract addressed to the "Rulers of America", which was distributed to members of Congress, a copy of which Washington signed and kept in his personal library.

[6] In his memoirs, Cooper documents his early life, family history, marriage, the birth of his children, his involvements with the Quakers, and the various struggles he faced with his faith.

He wrote the manuscript during his final years, for his children, when his health was failing, so that they would have a personal record of his life and work after he had died.

[8] As a dedicated Quaker and a staunch abolitionist[9] Cooper petitioned Congress three times in his effort to advance abolition legislature and abolish slavery, lobbied President George Washington, and wrote about these prospects at length in his diary and other writings.

It is thus we are to account for the fallacious reasonings and absurd sentiments used and entertained concerning negroes, and the lawfulness of keeping them slaves"[15]In 1785 Cooper, along with other Quakers, like Samuel Allinson, submitted petitions to the Legislature for purposes of enacting emancipation legislation.

[18][19][b] The pamphlet was a treatise written in strong and unforgiving terms, accusing American slaveholders of "treason" against the natural rights of man, and of making a "mockery" of the Declaration of Independence.

[22] Cooper published the tract with the intention that it be read aloud in the various colonies at a time when the Quakers were not in the best favor due to their non-violent and passive involvement in the American Revolution.

[21] "Now is the time to demonstrate to Europe, to the whole world, that America was in earnest, and meant what she said, when, with peculiar energy, and unanswerable reasoning, she pled the cause of human nature, and with undaunted firmness insisted, that all mankind came from the hand of their Creator equally free.

Let not the world have an opportunity to charge her conduct with a contradiction to her solemn and often repeated declarations; or to say that her sons are not real friends to freedom".

Cooper had written his Address anonymously, signing it A Farmer, to protect the Society of Friends from any responsibility of its controversial message,[25] and was displeased with Benezet that he had published his authorship and revealed his real identity.

In a letter of June 15, 1783, to Samuel Allinson, Cooper expressed his concerns about anonymity, protesting that Benezet "...knows how careful I was of having the author suspected.

[8] His ideas of abolition closely paralleled those surrounding indentured servitude in the American colonies where servants were required to serve for a given length of time, usually about seven years, and would be under the authority and discretion of their master.

Cooper's ideas first became public in 1772 when he published his A Mite cast into the Treasury...', where he asserted that, "every individual of the human species by the law of nature comes into the world equally entitled to freedom at a proper age."

Also, when Cooper made reference to female slaves, he explained "...till she came to the age of a woman, at which time she was pronounced free by the law of nature, and precepts of Christ."