There was a time, before Pyrex and Oxo, calculators and even cookbooks, when rules of thumb ruled the kitchen. My mother taught me my first one when I was six and still standing on a barstool to reach the kitchen faucet, the infamous and eerily accurate "one-knuckle" rule for cooking rice. Like all good R.O.T., the measures were flexible. It didn't matter how much rice or what size pot or what kind of stove. It worked.