Shin, as outer Action, represents the ShINing of the candle flame as it spreads out in ever expanding shells of radiant energy, light, and learning, from its Source. ShIN is also the outer Vessel that holds the Flame. As such its three "heads" define the shape of a Tetrahedron – which, as the most compact symmetrical 3-D form, represents an idealized Tooth, Notch, or Step. Since every Tetrahedron defines a complete sphere-cycle, it can also represent a year (ShaNaH). BeT makes distinctions, ShIN, its AT-BaSH twin, represents distinctions. That is why ShIN means Tooth, Notch, and Step. As a tooth, ShIN represents a "toothy grin" which ShINes out.