Hi guys, I just joined this site and I have my first question about counterpoint. Currently, I am studying 3rd Species in Two Parts (Chapter 3) and while I was analyzing one of the figures that Fux completed as an example (Figure 55), I noticed that in some places Fux placed a flat before the B note and in other places he didn't (thus a natural B note). Furthermore, Fux goes on to explain that he used the flats to avoid "harsh relations with Mi against Fa". I just don't understand how it could pertain to Mi against Fa. As previously stated in the book, Mi against Fa was explained as the tritone (Augmented Fourth/Diminished Fifth), but when I was analyzing one of the measures that used the flat on B the note sequence was: D, C, Bb, & A descending against the Cantus Firmus tone D. The following measure was: Bb, C, D, E ascending against the Cantus Firmus tone G. In my amateur eyes, I don't see anything that has to do with the Tritone harmonically. My only remote guess would be that he flatted the B because of the fact that it progresses into A which is a whole tone combination that is a part of the Tritone. Am I right?
Sorry for the incorrect grammar in the title, I tried to edit it but it wouldn't change lol.