Introduction Nor everybody burrow an instrument, but all like music. Exactly who does not touch, knows that the sequence of musical notes is d, reverse speed, mi, f, sun, there, itself. It is practically from these seven basic notes, and more five assistant (the sustenidos flats and) that the melodies of music occidental person are composed. One knows that music already was present since the first civilizations, but the notes differed from an instrument for the other, therefore rules for produziz them did not exist. It was then, second counts the legend, that Pitgoras, when passing in front of a blacksmith workshop perceived that the strokes of the hammers, which they differed for ratio (or fractions) from its masses, were pleasant to the ear and if they combined very well. To search these sounds, Pitgoras constructed an instrument, later called of monochord (mono = one and crdio one = rope), which if is similar to a violo of an only rope, working with measures of fractions on its experiment, the thinker of Samos very discovered interesting relations between a note and another one. Although not to be total certain on its existence, some of the posterior results that if also follow had been attributed to the Pitgoras.