To be conscious of abstracting is to differentiate among the "levels" described above; levels II-IV being abstractions of level I whatever level I "is"—all we really get are abstractions. The techniques Korzybski prescribed to help a person develop consciousness of abstracting he called "extensional devices". Satisfactory accounts of general semantics extensional devices can be found easily. This article seeks to explain briefly only the "indexing" devices. Suppose you teach in a school or university.