Bouzouki manner of a Neapolitan mandolins so as to increase the strength of the body to withstand thicker steel strings. The type of the instrument used in Rembetika music was a three-stringed instrument, but in the 1950s a four-string variety by Manolis Chiotis was introduced. From a construction point of view, the bouzouki can have differences not only in the number of strings but also in other features, e.g. neck length, width, height, depth of the bowl or main body, the width of the staves (the wooden gores or slices of the bowl) etc. These differences are determined by the manufacturer,
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: