The musical bards were divided into three classes. In the first were the players upon the harp; they were called doctors of music. To be admitted into this class it was necessary that they should perform successfully the three Mwchwl--that is, the three most difficult pieces in the bardic repertory. The second class of musical bards was composed of the players upon the crwth, of six strings. The third class were the singers. From the wording of the requirement it would seem that these must have had the same qualification as the first class, and therefore have been true doctors of music. For, in addition to being able to accord the harp or the crwth, and play different themes with their variations, two preludes and other pieces "with their sharps and their flats," they had to know the "three styles of expression," and accent them with the voice in different styles of song. They had also to know the twenty-four meters of poetry as well as the "twenty-four measures of music." Finally, they must be able to compose songs in many of these meters, to read Welsh correctly, to write exactly, and to correct an ancient poem corrupted by the copyists. The classification of new bards was made at an Eisteddfod once in three years. It was a public contest, after the custom of the Greeks. The degrees were three, conferred at intervals of three years respectively. The organization of the bards existed until the sixteenth century; it was suppressed under Queen Elizabeth. The Eisteddfod has been maintained until the present time. The learned musical historian, J.J. Fetis, attended one in 1829, of which he has left an interesting account. The performances of the blind minstrel of Caernarvon, Richard Robinson, excited his admiration beyond anything else that he mentions. He says: "His skill was something extraordinary. The modern harp of Wales has no pedals for the semitones in modulations. It is supplied with three ranks of strings, of which the left and right give diatonic notes, those in the middle the half-tones. Nothing more inconvenient could be imagined; in spite of his blindness, this minstrel, in the most difficult passages, seized the strings of the middle ranks with most marvelous address. The innate skill of this musician of nature, the calm and goodness painted upon his visage, rendered him an object of general interest." Independently of the minstrels of this high class, they had also wandering minstrels who played the crwth of three strings, and who made themselves useful in the customary dances and songs of the peasants and the common people.