The two elements of fire and water unite in the Temple. The two elements of air and earth unite in the Land of Israel.
In the Temple we offer sacrifices to God. The sacrifices ascend in flame on the altar. The Torah calls the sacrifices "fires." When offering a sacrifice we experience ourselves burning up and being consumed by God (the sacrifices are also referred to as God's "bread"). The experience is one of loving God with all our might – not just ready to die for God (would He so desire) but actually being consumed by Him, becoming a part of His very essence (as food becomes part of the body) – the highest level of loving God.
The Temple service reaches its apex on the festival of Sukot, "the time of our joy." Sacrifices are offered in abundance, including 70 cows, one for each nation on earth (making Sukot a universal festival). The joy of Sukot reaches its highpoint however not in animal sacrifice on the altar but with the pouring of living (i.e., spring) waters on the altar. These waters are described as being drawn in joy from "the fountains of salvation."
In the Temple of the future (described by Ezekiel, and which we contemplate and pray for daily) a tiny fountain of water issues from the Holy of Holies. As it passes through the Temple confines and exits the Temple Mount it grows wider and deeper until it becomes a mighty river that enters the sea and sweetens all the waters on earth, bringing healing and prosperity to all mankind.
In the idiom of Chasidut, the Temple fire is the experience that "God is all" (there is nothing but God, nothing else exists but Him) while the Temple water is the experience that "all is God" (all of reality is in essence Divine, and if "all is God" then all is good and sweet – there exist no more bitter waters on the face of the earth).
Of the Land of Israel it is said, "The air of the Land of Israel makes one wise." The air of Israel is conducive to one becoming wise in the wisdom of Torah, as it is said, "There is no Torah like the Torah of the Land of Israel." Wisdom is insight into the depths of reality (the secrets of creation) and a profound sense of intuition as to cause and effect in one's life.
The earth of the Land of Israel is holy. The sages ask, "Why was it called 'earth' [ארץ]? They answer, "Because it desired [רצתה] to do the will [רצון] of its Creator." "Earth" outside Israel also alludes to "will," but will which is not essentially aligned to God's will, as is the innate will of the Land of Israel.
And so, the air of Israel is the source of wisdom while the earth of Israel is the source of rectified will. Will and wisdom are the two most fundamental properties of the soul (corresponding to the first two sefirot). The Land of Israel nurtures both, as a mother breastfeeds her child. In contrast, the Temple experience is the truly "mature" experience of God Himself (beyond the rectification of our own soul).
We "grow up" in the Land of Israel, breathing its air and treading its earth, and then come to the Temple to see God (fire) and be seen by Him (water).