"We know a true poem to the extent to which our spirits respond to the spiritual appeal it makes," says Dr. Hiram Corson. It is the same with a true musical composition. We must take something to it, in order to receive something from it. Beyond knowledge comes the intuitive feeling which is enriched by knowledge. Through it we may feel the breath of life, the spiritual appeal, which belongs to every great work of art and which must forever remain inexplicable. VI The Piano and Piano Players When Pythagoras, Father of Musical Science, some six centuries before our era, marked and sounded musical intervals by mathematical division on a string stretched across a board, he was unconsciously laying the foundation for our modern pianoforte. How soon keys were added to the monochord, as this measuring instrument was named, cannot positively be ascertained. We may safely assume it was not slow in adopting the rude keyboard ascribed by tradition to Pan pipes, and applied to the portable organ of early Christian communities. After the tenth century the development of the monochord seems to have begun in earnest. Two or more strings of equal length are now divided and set in motion by flat metal wedges, attached to the key levers, and called tangents, because they touched the strings. In response to the demand for increased range, as many as twenty keys were brought to act on a few strings, commanding often three octaves. Guido d'Arezzo, the famous sight-reading music teacher of the eleventh century, advised his pupils to "exercise the hand in the use of the monochord," showing his knowledge of the keyboard. The keyed monochord gained the name clavichord. Its box-like case was first placed on a table, later on its own stand, and increased in elegance. Not until the eighteenth century was each key provided with a separate string. No unimped triumphal progress can be claimed for the various claviers or keyboard instruments that came into use. Dance music found in them a congenial field, thus causing many serious-minded people to regard them as dangerous tempters to vanity and folly. In the year 1529, Pietro Bembo, a grave theoretician, wrote to his daughter Helena, at her convent school: "As to your request to be allowed to learn the clavier, I answer that you cannot yet, owing to your youth, understand that playing is only suited for volatile, frivolous women; whereas I desire you to be the most lovable maiden in the world. Also, it would bring you but little pleasure or renown if you should play badly; while to play well you would be obliged to devote ten or twelve years to practice, without being able to think of anything else. Consider a moment whether this would become you. If your friends wish you to play in order to give them pleasure, tell them you do not desire to make yourself ridiculous in their eyes, and be content with your books and your domestic occupations."