Most of us think of ice as, well, ice, but if you're a bartender — especially a drink-slinger who belongs to the professorial cocktail brotherhood — ice is the most crucial part of a drink, if for no other reason than it comprises most of what's in your cocktail. The bartenders at Session Kitchen understand the physics of ice, and to prove it, they invested in the Rolls Royce of icemakers: a Clinebell, which makes 300-pound blocks of translucent, crystalline, pure ice, which they then sculpt into various shapes (spears, for example) to use in assorted cocktails. But what really separates Session Kitchen's ice program from other contenders is the seasonal ice cubes that change on a whim and have included blood orange, ginger beer and pressed apple. Drop one of those spherical cubes into a glass of whiskey, and every sip you take tastes completely different from the last because of the way the ice melts. Unorthodox? Probably. Clever? Definitely.