At the base of my right forefinger is an inch-and-a-half diagonal callus, yellowish-brown in color, where the heels of all the knives I've ever owned have rested, the skin softened by constant immersion in water. It distinguishes me immediately as a cook, as someone who's been on the job a long time. You can feel it when I shake my hand, just as I feel it on others of my profession. It's a secret sign, a sort of Masonic handshake without the silliness.