Review: Illustrated by Tony Ross. Is your glass half empty or half full? Misery Moo the pessimistic cow sees her glass empty but her loyal friend the happy-go-lucky lamb is always there to try to cheer Moo up. Inevitably the tables turn and Moo sees the impact her negativity has on her lamb. This light-hearted parable of friendship proves that attitude can be highly contagious but so can laughter.