Another cause of failure in invigorating a faculty, and increasing an organ by its active exercise, seems to be an inadequate temperament. What is excitement to the faculties and brain of a person of a quick nervous or sanguine temperament, may prove utterly unexciting to the faculties and brain of one with a low apathetic lymphatic temperament; and, consequently, improvement in the faculty and organ may follow in the former, while no change on either will occur in the latter. The susceptibility will thus vary according to the nature of the original constitution; and hence, in attempting to develope any mental power, we can expect to be successful only when we are certain that we have really the means of exciting and keeping up its activity. A mere passing stimulus will not suffice to increase nutrition and growth. Perhaps, also, we sometimes fail from applying a wrong stimulant. In seeking to improve a faculty, common sense dictates that it should be exercised upon its most agreeable and perfect productions. Thus, in cultivating a _taste for music_, we ought to present to the faculty the most beautiful and harmonious music, because that is the best calculated to excite it to agreeable and sustained activity. Accordingly, such is the plan by which we cultivate the taste in communities. But when we take an individual who has naturally no great liking for music, but in whom it is desirable that the talent should be developed, we do not stimulate the faculty to healthful exercise by daily accustoming it to the perception and discrimination of fine sounds, but we set him or her to labour for hours every day in producing sounds, remarkable at first only for being so discordant and disagreeable as to make every one keep as far from their source as possible; and thus our aim is defeated, and the taste injured rather than improved. It is true, that by stoical perseverance some arrive ultimately at the power of producing sounds pleasing to their own ears; but it will be found that it is only then that their musical faculty _begins_ to be improved, and that its activity is felt to be delightful. Many never arrive at that point, and, after years of ineffectual labour, give up the attempt in despair.