It not unfrequently happens to a musical composer that when a new idea occurs to him while he is extemporizing, it appears to him at the first moment more beautiful than he finds it to be on reconsideration. The Prince, who enjoyed extemporizing on the pianoforte, kept in his service a pianist, whose business it was to write down his inventions, which he played repeatedly to the pianist to enable him to sketch at once as faithfully as possible the chief ideas and modulations. These sketches the pianist, who was a talented musician, had to take home in order to work them out carefully according to the rules of musical composition. Having accomplished his task, he attended at the palace with the manuscript; and now it was his turn to play the new piece to his royal master. But, however anxious he had been to preserve intact the original ideas, he generally learnt to his concern that the music possessed no longer those beauties which had been dictated to him. Royal musicians who have studied Thorough Bass are sometimes formidable critics. At any rate, it would appear so from some musical criticisms of Frederick II., and of his sister the Princess Amalia. Frederick II. (Frederick the Great) King of Prussia (born 1712, died 1786) was a composer as well as a virtuoso on the flute. He regularly practised his instrument daily. In earlier life it was his habit to play the scales every morning as soon as he had risen from his bed; and he often performed in the evening five concertos on the flute, which his royal orchestra had to accompany. In composing he wrote down only the melody, and he indicated with it in words how the bass and the other parts should be contrived; for instance,--"Here the bass shall be in Quavers;"--"Here the violins shall play alone," etc. These directions he gave to his Kapellmeister Agricola, who then completed the score.