Regla. A threshold cast in clear glass in sand.
The threshold, often symbolizing a boundary or transition point, holds significance in the context of lost knowledge as it represents the point at which knowledge is either retained or lost. In referencing lost knowledge, the threshold signifies a critical juncture where valuable insights or understanding may be on the verge of disappearing into obscurity. It suggests a precarious state where the preservation of knowledge hangs in the balance, emphasizing the importance of recognizing and safeguarding it before it crosses the threshold into oblivion.