CC Madhya 21.30
śākhā-candra-nyāye kari dig-daraśana
“No one can estimate the opulence of Kṛṣṇa. That is unlimited. However, just as one sees the moon through the branches of a tree, I wish to give a little indication.”
First a child is shown the branches of a tree, and then he is shown the moon through the branches. This is called śākhā-candra-nyāya. The idea is that first one must be given a simpler example. Then the more difficult background is explained.