c. 800-c. 860

Arab mathematician and astronomer who wrote on Euclid's (c. 325-c. 250 B.C.) Elements and became the first to attempt a proof of the parallel postulate. Born in Baghdad, al-Jawhari was a member of the prestigious House of Wisdom, an institution of scholars established by the caliph al-Ma'mun (r. 813-833). In his Commentary on Euclid's Elements, al-Jawhari presented some 50 propositions in addition to those offered by Euclid, and attempted (though unsuccessfully) to prove the parallel postulate. As an astronomer, al-Jawhari made observations both from Baghdad and Damascus.