Central Illinois specializes in the storm that can't make up its mind — rain at dusk, ice by nine, a glaze on everything by the time the streetlights come up along Sheridan Road. That's the night Grass N More, Inc. is out spreading salt: driveways, walkways, the front step where a fall actually happens. Plowing follows when the snow does, pushed back past the mailbox so nothing melts and refreezes across the entrance. It is unglamorous work done in the dark, and the measure of it is that nobody thinks about it in the morning. Traction underfoot is a quiet sort of gift.