# A Dictionary of Music and Musicians/Ionian Mode

From volume 2 of the work.
​IONIAN MODE (Lat. Modus Ionicus, Modus Iastius). The Thirteenth—or, according to some writers, the Eleventh—of the Ecclesiastical Modes. [See Modes, the Ecclesiastical.]
The Final of the Ionian Mode is C. Its compass, in the Authentic form, extends upwards, from that note to its octave; and, as its semitones occur between the third and fourth, and the seventh and eighth degrees, its tonality corresponds exactly with that of the major diatonic scale as used in modern music—a circumstance which invests it with extraordinary interest, when considered in connexion with the history of musical science. Its Dominant is G—another point of coincidence with the modern scale. Its Mediant is E, and its Participant, D. Its Conceded Modulations are F, A, and B; and its Absolute Initials C, E, G, and frequently, in polyphonic music, D. Its chief characteristics, therefore, may be illustrated thus
Mode XIII (or XI).
The compass of the Plagal, or Hypo-ionian Mode, lies a fourth lower than that of the Authentic form, ranging from G to G. The Dominant of this Mode is E, its Mediant, A, and its Participant, G. Its Conceded Modulations are D, F, and the F below the initial G; and its Absolute Initials C, G, A, and, in polyphonic music, very frequently D.
Mode XIV (or XII).
It will be seen, that the semitones here fall between the third and fourth, and sixth and seventh degrees—exactly the position they occupy in the Authentic Mixolydian Mode: and, as the compass of these Modes is also identical, the one is often mistaken for the other, though they are as clearly distinguished, by their respective Finals, as the modern keys of E♭, and F♯ minor.
Though not included in the system set forth by St. Gregory, the Ionian and Hypo-ionian Modes are certainly as old as the 8th or 9th century: for, when the question of the number of Modes to be retained in use was submitted to the Emperor Charlemagne, he at first said that eight seemed to be enough, but afterwards authorised the employment of twelve, thus extending his indulgence to all except the notoriously impure Locrian and Hypolocrian. Eight Modes have, indeed, been always considered enough for the chaunting of the Psalms: hence, we find no Psalm Tones in either the Ionian or Hypo-ionian Modes; though ​other pieces of Ecclesiastical Music exist, in both. For instance, the fine Plain Chaunt 'Missa in Festis Solemnibus'—better known, perhaps, in a less pure form, as the 'Missa de Angelis' is in the Authentic Ionian Mode, throughout: and a particularly captivating Hypo-ionian melody has been preserved to us, in the Paschal form of the Responsory 'In manus tuas, Domine,' as given in the Mechlin Vesperal.
A strong prejudice existed against the Ionian Mode, in mediæval times, when the softness of its intervals gave so great offence, that it was commonly called Modus lascivus. The early contrapuntists seem also to have regarded it with grave suspicion. It was only as Art advanced, that the inexhaustible extent of its capabilities became gradually apparent. When first employed in polyphonic music, the Authentic scale was usually transposed (for the greater convenience of ordinary combinations of voices) with the customary B♭ at the signature; in which condition it is often mistaken for the modern key of F. Palestrina delighted in using it, with this transposition, as the exponent of a certain tender grace, in the expression of which he has never been approached; as in the 'Missa Brevis,' the Missa 'Æterna Christi munera,' the delightful Motets, 'Sicut cervus desiderat,' and 'Pueri Hebræorum,' and innumerable other instances. Giovanni Croce has also employed it in the Motet 'Virtute magna'—known in England as 'Behold, I bring you glad tidings': while in our own School, we find instances of its use in the imperishable little Anthem, 'Lord, for Thy tender mercy's sake,' and Gibbons's fine Service in F.
The Hypo-ionian Mode is less frequently transposed, in writing, than the Authentic scale, though it is sometimes found desirable to depress it a whole tone, in performance. This is the Mode selected, by Palestrina, for the Missa Papæ Marcelli; and by Orlando di Lasso, for his Motet, Confirma hoc, Deus—both which compositions are erroneously described, in the latest German reprints, as in the Mixolydian Mode.
[ W. S. R. ]