Benjamin Banneker, a self-taught surveyor and astronomer, mailed Secretary of State Thomas Jefferson a handwritten letter alongside a manuscript almanac filled with his own astronomical calculations. He asked Jefferson to abandon prejudices about Black intellectual capacity and to work toward abolishing slavery, invoking the same natural rights language Jefferson had used in 1776.
Banneker, born free in 1731 to a former slave father, taught himself advanced mathematics and astronomy well enough to accurately predict solar eclipses. In August 1791 he sent Jefferson a twelve-page letter enclosing a manuscript almanac with a full year of astronomical calculations, hoping to prove by example that Black Americans possessed the same intellectual capacities as white Americans.
His letter was pointed: he reminded Jefferson that he himself had once written of unalienable rights to life and liberty, then asked how this squared with holding fellow humans in bondage. He wrote that he hoped Jefferson would 'eradicate that train of absurd and false ideas' about racial inferiority.
Jefferson wrote back a polite, noncommittal reply, forwarding the almanac to a French scientific society as a curiosity rather than as proof of anything requiring policy change. Banneker's almanac was nonetheless published for several years afterward and became a rallying point for abolitionists, who reprinted the exchange as evidence against pseudo-scientific claims of racial hierarchy.