Mt 13:31 Another parable put he forth unto them, saying, The kingdom of heaven is like to a grain of mustard seed, which a man took, and sowed in his field:

Mt 13:32 Which indeed is the least of all seeds: but when it is grown, it is the greatest among herbs, and becometh a tree, so that the birds of the air come and lodge in the branches thereof.

Seed: Christ is the seed of the woman ([Ge 3:15]])

least of the seed: Jesus was the least among the seed since he served us all (Lu 7:28

herb: Jesus is the herb. The herbs were given to men to eat (Ge 1:29) and the body of Christ is the greatest thing men can eat (Mr 14:22).

tree: The cross is the tree upon which Christ hung (Ga 3:13).

air: The spirit (same word)

birds: Those who live in the spirit rest in the cross.

An example of The Kingdom of Heaven (the New Jerusalem or the new Teaching of peace) is Christ, "Who, being in the form of God, thought it not robbery to be equal with God:" (Php 2:6) instead became the least among men by serving us all with his death on the cross. He offered himself even unto death in order to redeem us. He hung on the cross as the ultimate expression of the love of God, and we can rest in him.