A Dictionary of Music and Musicians/Mi contra Fa

by William Smyth Rockstro

MI CONTRA FA. In pure Ecclesiastical Music, the use of the Tritonus, or Augmented Fourth, is strictly forbidden; as is also that of its inversion, the Quinta falsa, or Diminished Fifth. It is scarcely necessary to say that the presence of these intervals is felt, whenever F and B are brought either into direct or indirect correspondence with each other, whatever may be the Mode in which the contact takes place. Now, according to the system of Solmisation adopted by Guido d'Arezzo, B, the third sound of the Hexachordon durum, was called MI; and F, the fourth sound of the Hexachordon naturale, was called FA. Mediæval writers, therefore, expressed their abhorrence of the false relation existing between these two sounds, in the proverb—

Mi contra fa est diabolus in musica.

When the use of the Hexachords was superseded by a more modern system of immutable Solmisation (see Solmisation; Hexachord), F still retained its name of FA, while B took that of the newly-added syllable, SI: and the old saw then ran thus—

Si contra fa est diabolus in musica.

In this form it became more readily intelligible to musicians unacquainted with the machinery of the Hexachords; while its signification remained unchanged, and its teaching was as sternly enforced as ever. That that teaching continues in full force still is proved by the fact, that neither Pietro Aron, nor any other early writer, ever censured the 'False relation of the Tritone' more severely than Cherubini, who condemns it, with equal rigour, whether it be used as an element of Harmony, or of Melody.

[ W. S. R. ]