Portrait of a Killer: Jack the Ripper—Case Closed that a paper manufacture expert she hired asserts that reams of paper supposedly used by Jack the Ripper to write several letters to Scotland Yard and paper purchased by Sickert's mother bear the same small-press watermark. She also claims that there are matches in the cutter's marks, which are a result of the rough cutting of each quire (or small package) for packaging. A "quire" was usually of 24 sheets. Though Cornwell's book sold many copies, many Ripperologists and other critics argued that Cornwell's theory was far from persuasive. Critics also note that Cornwell has said that she did not
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: