Νικόμαχος Γερασηνός, (or Γερασινός), called Gerasenus, from his native place, Gerasa in Arabia, was a Pythagorean, and the writer of a life of Pythagoras, now lost. His date is inferred from his mention of Thrasyllus, who lived under Tiberius. He wrote on arithmetic and music, and is the earliest, we believe, of those whose names became bye-words to express skill in computation. In the Philopatris is the phrase "you number like Nicomachus of Gerasa." This writer exercised no small influence on European studies, in the fifteenth and sixteenth centuries; but indirectly. Boethius, in his arithmetical work, is no more than the abbreviator of the larger work of Nicomachus, now lost. The never-ending distinction of specific ratios by names (see Numbers, old appellations of, in the Supplement to the Penny Cyclopaedia), is the remote consequence of Nicomachus having been a Pythagorean.