In the most ancient church, their method of expressing themselves was such, that when they mentioned material and worldly things, they thought of the spiritual and celestial things that were represented. So they not only expressed themselves with representatives, but also lowered their thoughts into a kind of historical series, or arrangement, to give them life, and in this they found the greatest delight and entertainment. Those representatives are called 'hidden sayings of old,' in David's Psalm 78:2-4.

(References: Arcana Coelestia 66)