Units of paper quantity size and type of paper being sold. Reams of 500 sheets (20 quires of 25 sheets) were known in England in c1594; in 1706 a ream was defined as 20 quires, either 24 or 25 sheets to the quire. In 18th- and 19th-century Europe, the size of the ream varied widely. In Lombardy a ream of music paper was 450 or 480 sheets; in Britain, Holland and Germany a ream of 480 sheets was common; in the Veneto it was more frequently 500. Some paper manufacturers counted 546 sheets (21 quires of 26 sheets). J.S. Bach's manuscript paper at Weimar
How many angels can dance on the head of a pin? about how many could perch at the same time on the head of a pin"". Dorothy L. Sayers argued that the question was "simply a debating exercise" and that the answer "usually adjudged correct" was stated as, "Angels are pure intelligences, not material, but limited, so that they have location in space, but not extension." Sayers compares the question to that of how many people's thoughts can be concentrated upon a particular pin at the same time. She concludes that infinitely many angels can be located on the head of a pin, since they do not occupy any space there: