In January, 1766, we find him composing a song, "Conservati fedele" (23 K.), for the Princess of Weilburg, which consists of a pleasant, flowing melody, and here and there characteristic touches, happily expressed by changes of harmony. {HOLLAND, 1765-66.} (45) He was able before the end of this month to go on to Amsterdam, where they spent four weeks. Wolfgang gave two concerts at which all the instrumental pieces were of his own composition. Among them was a Symphony in B flat major (22 K.), in three movements, which had been written at the Hague, and which contains noteworthy instances of thematic elaboration and well-rounded phrasing. Although it was Lent, and all public amusements were strictly forbidden, these concerts were permitted because the "exhibition of the marvellous gifts of these children redounds to the glory of God," a resolution which, though it was formulated by Lutherans, was nevertheless cordially accepted by so devout a Catholic as L. Mozart. On March 8, 1766, they travelled back to the Hague, to assist at the festivities given in honour of the Prince of Orange, who came of age on that day. Wolfgang was ordered to compose six sonatas for piano and violin for the Princess of Weilburg, which were printed with a dedication (26 to 31, K.). In addition, he wrote several songs for the same princess, and other "trifles," which were also printed, among them pianoforte variations on an air composed for the occasion (24 K.), and upon another air, "which is sung, played, and whistled all over Holland." This was the song, "Wilhelmus von Nassau,"[20040] written and composed by Philipp von Mamix (d. 1598), on the Prince of Orange (d. 1584), which soon spread far and wide[20041] and became the national song of Holland. Mattheson cites it as an instance of a national war-song, which had inspired a whole people to great deeds, and had played an important part in the war and in the celebration of peace, in 1749.[20042] For one concert, Wolfgang composed an orchestral piece after the manner of a "Concerto grosso," in which a clavier obbligato was introduced with the other instruments and called it a "Galimathias musicum." Sketches for this in Wolfgang's handwriting, with his father's corrections here and there, have {FIRST JOURNEY.} (46) been preserved (32 K).[20043] After an easy andante, which serves as an introduction, come thirteen movements, generally only in two parts, varying both in measure and time. There is a variety of instrumentation unmistakably present, and the horns are specially favoured; there is one passage which imitates the bagpipes. [See Page Image] The whole winds up with an elaborate movement on the first part of the national song--