The modes used for Gregorian chants all begin on the note E.?

Gregorian chants primarily utilize modes, which are scales characterized by their unique sequences of whole and half steps. While some modes do begin on the note E, not all Gregorian chants are confined to this starting note; they can begin on various pitches depending on the mode used. The most commonly referenced modes in Gregorian chant are the Dorian, Phrygian, Lydian, and Mixolydian modes, each with its own tonal center. Therefore, it is inaccurate to say that all Gregorian chants begin on the note E.