A single image repeated without variation 49 times isn't
improvisation: it's a corpse. The repeat/repeat/repeat of a
single motif, a single cliche, comes to life and has meaning
only with variation, however slight. Otherwise it's fixed and
lifeless.

The secret of any tribal beat is that its underlying
rhythm, its deep structure pattern, remains unbroken while
variations occur on the surface level. It's like a Five-times
Table where one can improvise indefinitely as long as one
obeys the rules of multiplication. There's no point, of
course, in learning these rules unless one wants to
improvise. —Edmund Carpenter