A metaphor is when something is used to represent something else. True metaphor also has allegorical connections. The properties or attributes of the metaphor relate to the idea through word-play and/or riddle. Sometimes we call it shadow .
A simple example of this is the stone. The Greeks use 'rock' as a symbol for Christ, but only because he refers to himself as the rock and because Paul calls him the rock. It is merely a substitution and a weak memory of the true metaphor. The Hebrew word for 'stone' is aben אבן. It consist of father ab and son ben. Every stone becomes a metaphor for the Father and Son together. When it is split, it is a picture of the cross when the Father left the Son.  The stone as a metaphor of the Father and Son may be seen from a different angle as the revelation of the Father and the Son, or the Word. When the word is split, judgement is removed, leaving grace. When someone was stoned, they were convicted by the word/stone of God.
Mark uses these shadows or metaphors from the scriptures as he describes John to indicate John is fulfilling prophetic riddles. He is revealing the mystery.
- Mr 1:6 And John was clothed with camel’s hair , and with a girdle of a skin  about his loins  ; and he did eat locusts  and wild honey  ;
There is a physical resemblance, like a costume, that John adopted to point to Elijah as a hairy man who wore a leather girdle.  However, Mark does not stop there, he includes the details of eating locusts and honey. Two items which are clear physical allusions are increased to a count of four. By doing so, he calls attention to the four voices of God in revealing his word: prophet, priest, king and judge. The four items may be mapped to the four voices.
Mark is suggesting that Elijah was a metaphor for all four voices, and is inviting us to dig deeper to see how.
- Four animals carry bread.
- One receives his own water.  
- Jesus rode on the colt of an ass that had never been bridled  
- One must die and rise again.  
- One is used in sacrifices.
- Heb 10:1 ¶ For the law having a shadow of good things to come, [and] not the very image of the things, can never with those sacrifices which they offered year by year continually make the comers thereunto perfect.
- Mt 27:46 And about the ninth hour Jesus cried with a loud voice, saying, Eli, Eli, lama sabachthani? that is to say, My God, my God, why hast thou forsaken me?
- The stone is the heavenly representation of the Father and Son, and the rock is the earthly. To be precise, the rock was split and the stone was shattered. The theological implications are too small to discuss this early in the conversation.
- The authority (hair) of a judge (camel)
- Kings girdle אזור of righteousness (skin עור is a pun to lightאור )
- as a gift מתן (Elijah was righteous as a gift)
- 2Ki 1:8 And they answered him, [He was] an hairy man, and girt with a girdle of leather about his loins. And he said, It [is] Elijah the Tishbite
- The increase/hidden/church ארבה. He ate the body of Christ. This is a symbol of the priest.
- The word דב of marriage ש. The prophecy of Christ as the bridegroom in the flesh.
- 2Ki 1:8 And they answered him, [He was] an hairy man, and girt with a girdle of leather about his loins. And he said, It [is] Elijah the Tishbite.
- 1Ch 12:40 Moreover they that were nigh them, [even] unto Issachar and Zebulun and Naphtali, brought bread on asses, and on camels, and on mules, and on oxen, [and] meat, meal, cakes of figs, and bunches of raisins, and wine, and oil, and oxen, and sheep abundantly: for [there was] joy in Israel.
- Ge 24:11 And he made his camels to kneel down without the city by a well of water at the time of the evening, even the time that women go out to draw water.
- Ge 24:19 And when she had done giving him drink, she said, I will draw water for thy camels also, until they have done drinking.
- Ge 24:20 And she hasted, and emptied her pitcher into the trough, and ran again unto the well to draw water, and drew for all his camels.
- Mr 11:2 And saith unto them, Go your way into the village over against you: and as soon as ye be entered into it, ye shall find a colt tied, whereon never man sat; loose him, and bring [him].
- The mother was brought to lead the colt Mt 21:2 Saying unto them, Go into the village over against you, and straightway ye shall find an ass tied, and a colt with her: loose [them], and bring [them] unto me.
- This is a tough one: Jesus as king had to die and could not rule as king until he rose again
- The word for a 'mule' is also the word for 'seed'.