But the revival of a more worldly civilisation in the cities of the late Middle Ages had created a new demand for musicians. Instruments like the horn, which had been used only as signal-instruments for hunting and fighting, were remodelled until they could reproduce sounds which were agreeable in the dance-hall and in the banqueting room. A bow strung with horse-hair was used to play the old-fashioned guitar and before the end of the Middle Ages this six-stringed instrument (the most ancient of all string-instruments which dates back to Egypt and Assyria) had grown into our modern four-stringed fiddle which Stradivarius and the other Italian violin-makers of the eighteenth century brought to the height of perfection. And finally the modern piano was invented, the most wide-spread of all musical instruments, which has followed man into the wilderness of the jungle and the ice-fields of Greenland. The organ had been the first of all keyed instruments but the performer always depended upon the co-operation of some one who worked the bellows, a job which nowadays is done by electricity. The musicians therefore looked for a handier and less circumstantial instrument to assist them in training the pupils of the many church choirs. During the great eleventh century, Guido, a Benedictine monk of the town of Arezzo (the birthplace of the poet Petrarch) gave us our modern system of musical annotation. Some time during that century, when there was a great deal of popular interest in music, the first instrument with both keys and strings was built. It must have sounded as tinkly as one of those tiny children's pianos which you can buy at every toy-shop. In the city of Vienna, the town where the strolling musicians of the Middle Ages (who had been classed with jugglers and card sharps) had formed the first separate Guild of Musicians in the year 1288, the little monochord was developed into something which we can recognise as the direct ancestor of our modern Steinway. From Austria the "clavichord" as it was usually called in those days (because it had "craves" or keys) went to Italy. There it was perfected into the "spinet" which was so called after the inventor, Giovanni Spinetti of Venice. At last during the eighteenth century, some time between 1709 and 1720, Bartolomeo Cristofori made a "clavier" which allowed the performer to play both loudly and softly or as it was said in Italian, "piano" and "forte." This instrument with certain changes became our "pianoforte" or piano.