18.35Hear major versus Lydian

Play over Cmaj7:

C major scale includes F.

Then C Lydian includes F♯.

Compare:

F over Cmaj7

with:

F♯

F sits a semitone above E, the major third, which can sound tense.

F♯ gives a more luminous/open maj7 sound.

This is why jazz theory often associates Lydian with certain major chords.