one or many turtles

«This reflects our belief that a self-watching system should not be
organized as a rigid hierarchy of distinct levels, with each level
responsible only for detecting and responding to patterns occurring at
the level immediately below it, implying the need for an infinite stack
of separate "watcher" mechanisms. Instead, a single set of mechanisms
should be capable of detecting first-order patterns, higher-order
patterns within these patterns, patterns of patterns of patterns, and so
on, with all levels fused together and no limit in principle on the
potential complexity of the patterns involved (Hofstadter, 1985a).»