Pivot tones in the minor mode in Schoenberg's Theory of Harmony

Hello!

I am currently reading Schoenberg's Theory of Harmony and I just arrived at the Minor Mode chapter where he begins to discuss the use of pivot tones in order to use leading notes within the Natural Minor scale. I guess in a way pivot tones are way of using the leading tone progression possible with the Melodic Minor scale while still maintaining the tonal impressions of the Natural Minor scale.

I'm just really confused when I try to put these theories into practice and I get this impression that Schoenberg is contradicting the rules he set down at the beginning of the chapter in his examples (which I'm sure he's not and it's probably just my confusion if anything). I think it mainly has to do with when he talks about "chromatic raising" on page 102; using the A minor scale in these examples he talks about how if "two successive chords employ f [subtonic] and f sharp [leading note] respectively, then the same voice that had the f must take the f sharp respectively". However I thought that the rules he set up at the beginning of the chapter stated that f must go to e since it belongs to the descending form of the scale (natural minor) and f sharp must go to g sharp since it is apart of the ascending form of the scale (melodic minor). I'm just confused about how chromatic movement can be used without compromising the laws of the pivot tones.

I apologize if any of this sounds confusing; in fact it might only make a little sense for someone who has read this book. In any case I'm mainly asking if anyone has either read this specific chapter in the book and can help me understand or if anyone could recommend any theory books with regards to handling pivot tones within the Minor Mode.

Thanks for reading this and i hope to hear from you soon,

Pete.