The letter shin appears engraved on both sides of the head- tefilin. On the right side, the shin possesses three heads, while on the left side it possesses four heads. In Kabbalah we are taught that the three-headed shin is the shin of this world while the four- headed shin is the shin of the World to Come.
The secret of the shin is "the flame [Divine Revelation] bound to the coal [Divine Essence]." A simmering coal actually possesses an invisible flame within it, which emerges and ascends from the surface of the coal when the coal is blown upon. The three levels: coal, inner flame, and outer flame, correspond to the secret of chash-mal-mal, as will be explained in the next letter, the tav.
One of the meanings of the word shin in Hebrew is shinui, "change." The coal symbolizes changeless essence, the secret of the verse: "I am God, I have not changed," meaning that relative to God's Essence absolutely no change has occurred from before Creation to after Creation. The inner flame is the paradoxical latent presence of the power of change within the changeless. The outer flame of the shin is continuously in a state of motion and change.
As in the above-quoted verse, the changeless Essence is the secret of the Name Havayah. The power of change, as latently present within God’s Essence before Creation and thereafter revealed in the infinite intricacy and beauty of an ever-dancing flame, is the secret of the explicit Name of Creation, Elokim, the only Name of God which appears in the plural. The number of the letter shin, 300, unites these two Divine Names as the "flame bound to the coal." In at'bash, the Name Havayah transforms to the letters mem-tzadik-pei-tzadik, which total 300. The five letters of Elokim (alef-lamed-hei-yud-mem) when written in full, also equal 300.
The three heads of the shin of this world correspond to the three levels of the changeless, potential, and actual change as discussed above. In this world, the changeless is symbolized only by a black, dark coal, not as the revealed light of the flame. Nonetheless the endurance of the flame depends upon the changeless essence of the coal. In the World to Come, the changeless essence will reveal itself within the flame. This revelation of the future is the secret of the fourth head of the shin.
In the flame of a candle one sees three levels of light: the "dark light" around the wick of the candle, the white flame encompassing it, and an amorphous aura around the white flame itself. Each of these three levels of revealed light manifests a dimension contained within the invisible flame present in the coal. In general the flame symbolizes love, as is said: "as mighty as death is love...the flame of God." The dark light corresponds to the love of Israel, souls enclothed within physical bodies. The white light corresponds to the love of Torah. The aura corresponds to the love of God. These are the three essential manifestations of love as taught by the Ba'al Shem Tov. The fourth head of the shin of the future - the revelation of the essence of the coal itself - corresponds to the love of the Land of Israel and, as our Sages teach: "the Land of Israel will in the future spread to incorporate all the lands of the earth."
Three vavs, each with a yud on top, rise from a common base- point.
Symbol of symmetry; Form of a flame.
A year; change; a tooth; scarlet; serenity; to sleep; to teach; two; sharp; old; viceroy.