Trinity Sunday

The scholastic theologians, teachers that they were, came up with a numbered mnemonic for keeping the doctrines on the Trinity in mind:

1 nature: deity

2 processions: the Word and the Spirit. The Word proceeding from the Father, and the Spirit proceeding from them both. Thus we are led to...

3 persons: Father, Son and Spirit. And the two processions lead to relationships imagined from both directions, leading to...

4 relations: paternity, filiation, and active and passive spiration. And we add to these 4 relations the unbegottenness proper to the Father, we get

5 notions: paternity, filiation, active and passive spiration, and unbegottenness.

Thus we come to the famous frustrated formulation of theology students everywhere:

5 notions
4 relations
3 persons
2 processions
1 nature
and ZERO understanding!