A hierarchy (in Greek hieros, sacred, and arkho, rule) is a system of ranking and organizing things.
Hierarchy is a subset of context. Human knowledge is hierarchical, because higher-level abstractions depend on lower-level knowledge, all the way down to perceptual evidence. For example, in the simple case of the conceptual chain from the higher concept "furniture" to "coffee table":
|Senses | Consciousness | Volition | Concepts: Unit, Concept-Formation|
|Objectivity | Knowledge: Context, Hierarchy | Reason: Certainty, Truth, the Arbitrary | Emotions|