Exodus 3:1 Now Moses kept the flock of Jethro his father in law, the priest of Midian: and he led the flock to the backside of the desert, and came to the mountain of God, even to Horeb. [kjv]
και μωυσης ην ποιμαινων τα προβατα ιοθορ του γαμβρου αυτου του ιερεως μαδιαμ και ηγαγεν τα προβατα υπο την ερημον και ηλθεν εις το ορος χωρηβ [lxx]
3:2 And the angel of the LORD appeared unto him in a flame of fire out of the midst of a bush: and he looked, and, behold, the bush burned with fire, and the bush was not consumed. [kjv]
ωφθη δε αυτω αγγελος κυριου εν φλογι πυρος εκ του βατου και ορα οτι ο βατος καιεται πυρι ο δε βατος ου κατεκαιετο [lxx]
Go back to the time after Moses left Egypt the first time and was in Midian. What does the bush represent? This bush is the acacia bush which is a thorny bush. What do thorns represent?
Fire, in the Levitical sense, represented judgment. Brass, such as the brass pole with the serpent, could withstand fire. How could a thorny bush burn but not yet be consumed? Is that not strange?