And then, in passing, they notice me, the big man with the tight haircut. There is nothing about me--even the straight, stiff way I carry myself--that signals disabled. Until people notice the cane in my left hand, that is, and the way I lean on it every few steps. Then they realize my stiff walk and straight posture aren't just pride, and that Tuesday isn't just an ordinary dog. He walks directly beside me, for instance, so that my right leg always bisects his body. He nuzzles me when my breathing changes, and he moves immediately between me and the object--a cat, an overeager child, a suspiciously closed door--any time I feel apprehensive. Because beautiful, happy-go-lucky, favorite-of-the-neighborhood Tuesday isn't my pet; he's my service dog."