Irish bouzouki when having a longer scale length. The fifth course is usually either a lowest bass course tuned to C2 or D2 on an instrument with a long scale, or a highest treble course tuned to G4 or A4 on a shorter scale. Luthier Stefan Sobell, who coined the term "cittern" for his modern, mandolin-based instruments, originally used the term for short scale instruments irrespective of the number of their strings, but he now applies "cittern" to all 5 course instruments irrespective of scale length, and "octave mandolin" to all 4 course instruments, leaving out bouzouki entirely. Mandolin-family luthiers producing an
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: