I suffer from a motor neuron disorder, in my case a variant of amyotrophic lateral sclerosis (ALS): Lou Gehrig's disease. Motor neuron disorders are far from rare: Parkinson's disease, multiple sclerosis, and a variety of lesser diseases all come under that heading. What is distinctive about ALS—the least common of this family of neuro-muscular illnesses—is firstly that there is no loss of sensation (a mixed blessing) and secondly that there is no pain. In contrast to almost every other serious or deadly disease, one is thus left free to contemplate at leisure and in minimal discomfort the catastrophic progress of one's own deterioration.