Reddit mentions of Compositional Theory in the Eighteenth Century

>I know that during his time, Fux wrote his book on counterpoint, but Bach already mastered counterpoint long before it was published.

The following authors present species counterpoint over a century before Fux's Gradus ad parnassum (1725):

Lanfranco - 1532

Zarlino - 1558

Diruta - 1593

Zacconi - 1596

Banchieri - 1614

Bach, like most musicians of his time and place, also had extensive familiarity with thoroughbass. Joel Lester has a great discussion of these things and more in Compositional Theory in the Eighteenth Century. Also look into Robert Gauldin - A Practical Approach to 18th Century Counterpoint.

yeah, i win

do yourself a favor and read this before you start spouting off about things about which you know nothing