THIS week, four times as many self-help books will be sold as in any other week of the year. Very few of them -- even those expounding fanciful theories and recommending eccentric diets -- can do very much harm, and most of them can do a lot of good.
The great majority are based, sometimes without the authors' knowledge, on precepts centuries old but none the worse for that. Long before the 21st century, exercise, healthy diet and general good behaviour were hardly secrets. They do not change over time, but wilful human nature needs constant reminders.
Among the purchasers this week will be people who want to fortify themselves in their New Year resolutions, but also some who have already fallen prey to tobacco, chocolate and other temptations and seek encouragement to get back on the right path.
The books will give them programmes and incentives as well as basic good advice. But it takes no self-help expert to identify one of the biggest problems of the age and tender one of the shortest and simplest injunctions: Get up off that couch!
Far too many need that advice. And most of them are not the supposedly typical middle-aged couch potatoes. Obesity in adolescence, even in childhood, has become an increasingly frequent and highly disturbing phenomenon. It dulls the mind and harms the body. And the cure is in the hands of parents, more than in the pages of a book.