The admission of thirds and sixths even grudgingly among the consonant intervals is proof that through some common or popular practice of singing they had become familiar and pleasant to the ears of men. We have already mentioned the possible origin of organum in the practice of improvising counter-melodies which seems to have existed among the Celts and Germans of Europe at a very early age. There is some reason to believe that in this practice thirds and sixths played an important rôle; in fact, that there were two kinds of organizing or descant, one of which, called _gymel_, consisted wholly of thirds, the other, called _faux-bourdon_, of thirds and sixths. These kinds of organizing, it is true, are not mentioned by name until nearly the close of the fourteenth century, but there is evidence that they were of ancient origin. Whether or not these were the popular practices which brought the agreeable nature of thirds and sixths to the attention of the mensuralists has not yet been definitely determined. The reader is referred to Dr. Riemann’s _Geschichte der Musiktheorie im IX-XIV Jahrhundert_ (Leipzig, 1898), and the 'Oxford History of Music,’ Vol. I, by H. E. Wooldridge (Part I, p. 160), for discussions on both sides of the question. The word gymel was derived from the Latin _gemellus_, meaning twin, and the _cantus gemellus_, or organizing in thirds, in fact, consists of twin melodies. _Faux-bourdon_ means false burden, or bass. The term was applied to the practice of singers who sang the lowest part of a piece of music an octave higher than it was actually written. If the chord C-E-G is so sung then it becomes E-G-C, and whereas in the original chord as written the intervals are the third, from C to E, and the fifth, from C to G, in the transposed form the intervals are the third, from E to G, and the sixth, from E to C, of which intervals _faux-bourdon_ consisted. The origin of this 'false singing’ offered by Mr. Wooldridge,[68] though properly belonging in a later period, may be summarized here.