In the Introduction it was suggested that ‘mental health’ was something important, not only for experts but for every individual : and also that it was something which, in a sense, individuals could only acquire for themselves or be helped to acquire—not something which could be handed to them on a plate. This is, however, true only of one aspect of mental health. It is a crucially important aspect, and the one which is of greatest concern to teachers and education in general : and we must begin by making clear what aspect we are talking about.