Hi Adrien, I'm currently working on Lesson 3 of "Swing Mastery" ("My Blue Heaven") and I had a question. You mention that we need to flatten the 9th of a dominant chord if this chord is going to a minor chord. In this case, flatten the 9th of our D9 arpeggio because the following chord is Gm. Would it be possible to give us some more theory behind it. My understanding is that flattened 9th acts a leading tone to the 6th of Gm, but maybe there is another reason? Thanks!