They used to call it the _Diabolus in musica_.
Palestrina was the first to employ it in an anthem.

Opinions differ on this, and certain students of harmony pretend that the chord which Palestrina used only has the appearance of the dominant seventh.

I do not concur in this view.

But however the case may be, the glory of unchaining the devil in music belongs to Montreverde.

That was the beginning of modern music.
Later, a new third was superimposed and they dared the chord _sol-si-re-fa-la_.