Ionian

Major under an old name

The article The modes through familiar pieces explains: if you play only the white keys on the piano from C to C, C major sounds. If you play the same keys from D to D, something different sounds, with the same notes but a different reference point. That is how the seven church modes arise, Ionian from C, Dorian from D, Phrygian from E, Lydian from F, Mixolydian from G, Aeolian from A and Locrian from B. Ionian is identical to major, Aeolian to natural minor. The other five are what is usually meant when modes are spoken of.

Modes and diatonic chords

In its table of the diatonic chords of C major the page Circle of fifths assigns each degree a mode, if you begin on the degree in question. The first degree has the major chord C and the mode Ionian.

That a mode arises not from the choice of notes but from the emphasis is recorded by the article. If you play the white keys over a drone on D but keep ending the phrases on C, you have C major again. In Ionian, by contrast, the reference note lies on C.

Common mistakes

• Taking Ionian for a new sound: It is major.
• Defining the mode by the notes used: What matters is the reference note.
• Taking all modes as equivalent: Locrian remains, according to the article, a marginal case, because the triad on its root is diminished.