The Great Chain of Being
Although popular during the Renaissance, the belief in an ordered universe predates Christianity. This particular system, though, was well suited to the precepts of Christianity and Roman Catholicism, in particular.

The cosmos, creation, follows a hierarchial order leading upwards to a being of pure form; this Necessary Being relies on only itself for existence. (Thomas Aquinas's Prime Mover)

Everything in the universe has a place in the hierarchy; the universe is ordered. This ordering is natural, and any attempt to circumvent the order is unnatural and potentially destructive. If the Necessary Being is the Christian God, then an unnatural act is a sin; it disrupts God's order, plan.

  • Necessary Being: God (Pure Form)
  • Contigent Beings (rely on some other being)
    • Angel
    • Man
    • Animal
    • Plant
    • Mineral
  • Chaos (Prime Matter)

    Humanity (man), for example, could be further subdivided.

    • Pope
    • Cardinal Bishop
    • Cardinal Priest
    • Cardinal Deacon
    • Priest

Some Other Sources