Mozart had heard the "Messiah" in 1777 at Mannheim, but apparently it had made no more lasting impression upon him than upon the public. Now, however, he approached the masterpiece with far other predilections, and the adaptation opened to him many points of interest. The three oratorios already mentioned were so moderate in length as to be suited for performance entire, but the greatly {THE "MESSIAH."} (223) disproportionate length of the "Messiah" made its curtailment a necessary part of its adaptation (572 K.). Several pieces were omitted, and others were shortened; but a proof that other and more important alterations were contemplated is afforded by a letter from Van Swieten to Mozart (March 21, 1789), given by Niemetschek (p. 46): "Your idea of turning the words of the unimpassioned air into a recitative is excellent; and in case you should not have retained the words, I have copied and now send them to you. The musician who is able to adapt and to amplify Handel's work so reverently and so judiciously, that on the one side he satisfies modern taste, and on the other preserves the integrity of his subject, has appreciated the great master's work, has penetrated to the source of his inspiration, and will doubtless draw from the same well himself. It is thus that I regard what you have accomplished, and I need not therefore again assure you of my entire confidence, but only beg you to let me have the recitative as soon as possible." Nevertheless, this idea, judging from the published score, was not carried out. In the arrangement of the orchestra, Mozart has gone further than in the previous works. Sometimes there has been an external necessity for altering even characteristic instrumentation, as in the air, "The trumpet shall sound" (No. 44). There were no solo trumpeters such as existed in Handel's time, and an attempt was made to preserve the effect as far as possible by rearrangement. He has altered, however, even without such occasion as this, and many instances of instrumental arrangement might be cited as far transgressing the bounds within which interference with a work of art is justifiable.[19] In themselves these same portions are admirable alike in their sound-effects and musical treatment, and in the delicate discrimination with which Mozart has made his additions appear as the natural development of Handel's ideas; we can see how the fascination of continuing the weaving of the threads from the master's hands has tempted {OFFICIAL AND OCCASIONAL WORKS.} (224)