But the Psaltery was a great stride forward. This instrument was an arrangement of _strings on a box_. Here we have the principle of the sounding-board,--a thing of vital moment to the piano, and one upon which the utmost care is bestowed by all the great makers. Whoever first thought of stretching strings on a box may also be said to have half invented the guitar and the violin. No single subsequent thought has been so fruitful of consequences as this in the improvement of stringed instruments. The reader, of course, will not confound the psaltery of the Middle Ages with the psaltery of the Hebrews, respecting which nothing is known. The translators of the Old Testament assigned the names with which they were familiar to the musical instruments of the Jews. About the year 1200 we arrive at the Dulcimer, which was an immense psaltery, with improvements. Upon a harp-shaped box, eighteen to thirty-six feet long, fifty strings were stretched, which the player struck with a stick or a long-handled hammer. This instrument was a signal advance toward the grand piano. It _was_ a piano, without its machinery. The next thing, obviously, must have been to contrive a method of striking the strings with certainty and evenness; and, accordingly, we find indications of a keyed instrument after the year 1300, called the Clavicytherium, or keyed cithara. The invention of keys permitted the strings to be covered over, and therefore the strings of the clavicytherium were enclosed _in_ a box, instead of being stretched _on_ a box. The first keys were merely long levers with a nub at the end of them, mounted on a pivot, which the player canted up at the strings on the see-saw principle. It has required four hundred years to bring the mechanism of the piano key to its present admirable perfection. The clavicytherium was usually a very small instrument,--an oblong box, three or four feet in length, that could be lifted by a girl of fourteen. The clavichord and manichord, which we read of in Mozart's letters, were only improved and better-made clavicytheria. How affecting the thought, that the divine Mozart had nothing better on which to try the ravishing airs of "The Magic Flute" than a wretched box of brass wires, twanged with pieces of quill! So it is always, and in all branches of art. Shakespeare's plays, Titian's pictures, the great cathedrals, Newton's discoveries, Mozart's and Handel's music, were executed while the implements of art and science were still very rude.