Pappus was the last notable Greek mathematician and is chiefly remembered because his writings contain reports of the work of many earlier Greek mathematicians that would otherwise be lost. His chief work, Synagogue (c. 340; Collection), consisted of eight books of which the first and part of the second are now lost. It was intended as a guide to the whole of Greek mathematics and this is what makes it such a significant historical source. Among the mathematicians whose work Pappus expounds are Euclid, Apollonius of Perga, Aristaeus, and Eratosthenes. Pappus did contribute some original work, however, notably in projective geometry.

As with many Greek mathematicians Pappus was as interested in astronomy as in pure mathematics and his other work included comments on Ptolemy's astronomical system contained in the Almagest.