the guru said, “the first kōan appeared on monday, the second kōan on tuesday, the third on wednesday, the fourth on thursday, and the fifth on friday. for the second week, the numbers ran from six to ten. this meant that monday’s kōan number could all be represented by the form 5n+1 for any positive integer n, less than or equal to the number of kōans divided by 5. and, more generally, each kōan number could be represented by the form 5n+y, where y corresponded to the designated number for that day of the week, monday being 1, tuesday being 2, and so on. however, as time went by, this began to bother me: should not the first kōan be labeled 0? so i switched to that system, with monday’s kōan numbers being represented 5n+0, or just 5n, which i liked more in theory but which bothered me in practice: friday’s numbers all ended in 4 and 9, rather than 5 and 0, which seemed less satisfying at the end of a long week of kōaning, and so i solved that problem by slacking off and missing a few kōans, which got us to our current system.”

the tortoise said, “and you wonder why people say your lectures are boring.”