The young musician has soon to commence the study of the theory of music, especially if he exhibits decided talent for composing. He must learn to write with facility any musical composition strictly according to the rules which have been laid down by our theorists as they found them observed in the works of the great masters. When he has acquired the skill to write correctly and fluently in the different forms of composition, it will be early enough for him to disregard the rules occasionally where he thinks it advisable for his purpose. Perhaps he may establish a new one. By far the greater number of our rules of composition are not dictated by any physical law traceable in acoustics, but only by human taste, which is continually undergoing modifications in the course of time. Thus, most of our great composers have caused some alterations in our theory of music. It is not only possible, but probable, that in a hundred years' time we shall have admirable musical compositions very different in form and construction from our present ones. Several of our great composers in their youth excelled in extemporising. They were fond of it, and spent many an hour in pouring forth on their favourite instrument their momentary inspirations and fanciful conceptions. Extempore fantasias are sometimes so original and effective that it is a pity they cannot be preserved by being committed to notation at the moment of their creation. However, charming as such spontaneous effusions may be on account of their freshness, they do not possess the artistic value of an elaborately constructed and carefully finished work. At any rate, our great composers have in their youth derived greater benefit from carefully working out in notation a theme according to a certain form of composition, than from indulging in extempore fantasias. These have, however, often helped them in creating beautiful ideas for their works.