Once, during their travels, being detained by a heavy shower at Ypps, they took refuge in a monastery. The monks were at supper and did not know of the arrival of any stranger, until suddenly from the chapel came wonderful music, music grave and gay, sad, sweet, thrilling, and marvellous in its appeal to hearts and souls. The Fathers were frightened, not knowing who could have entered their sanctuary, thinking it must be a spirit, when at last a light was brought, and creeping into the chapel, they discovered little Wolfgang at the organ, not a vision, but just a mortal boy. The Fathers were overcome with amazement and lavished all possible courtesies on the wonderful little musician and his family while they remained. On entering Vienna, at the Custom House, Wolfgang, after a brief chat with the official there, took out his violin, and played to the official, who was so delighted with the boy and his music, that the family had no trouble with examination of their luggage, as they would otherwise have had. The Imperial family of Vienna were all very fond of music, and had also had their curiosity greatly excited in regard to this child prodigy, so it was not strange that only a few days after the Mozarts arrived, Leopold should have received a command to bring his children to play at Schoenbrum, an imperial palace near Vienna, and this without any effort on Mozart's part to get the invitation. The Emperor was delighted with the little "sorcerer" as he called Wolfgang, and besides listening to his real playing with deepest interest, he made him play with one finger, in which the little fellow was perfectly successful. Then he asked him to play with the keys covered by a piece of cloth, which he did instantly, and these musical tricks suggested by the Emperor's fancy, thereafter formed a far from unimportant part of Wolfgang's repertoire on his long concert tours, and always interested his audiences. The boy had a keen sense of humour, and always entered heartily into any joke that was made with him, but sometimes he could be very serious, as for instance, when he was called to play for the court composer, George Wagenseil, who was himself a proficient performer on the harpsichord. The Emperor stepped back when Wagenseil came forward, and Mozart said very seriously to him: "I play a concerto by you, you must turn over the pages for me," and turn the pages the great man did. The Emperor ordered one hundred ducats to be paid to Wolfgang's father for the performance, and the Empress, both then and later, was kindness itself to both the children, and sent them expensive and beautiful clothes. In writing to a friend at that time, Leopold Mozart said: "Would you like to know what Wolferl's dress is like? It is the finest cloth, lilac-coloured, the best of moire of the same colour. Coat and top-coat with a double broad border of gold."