Gregory the Dialogist

Which ephod is also rightly ordered to be made of gold, blue, purple, twice dyed scarlet, and fine twined linen, that it may be shewn by how great diversity of virtues the priest ought to be distinguished. Thus in the priest's robe before all things gold glitters, to shew that he should shine forth principally in the understanding of wisdom. …

The Book of Pastoral Rule, Part 2, Chapter 3 ↗