Must contain good counterpoint: mostly contrary and oblique motion (some
similar motion is OK), usually motivically independent from the subject,
no parallel perfect intervals, dissonances must be explained as either
passing, neighbor, escape, appogiatura, suspension, or retardation (dissonances
can be accented [on-the-beat]).
Often countersubject is invertible: it can be stated either above or below
subject. To accomplish this you must write mostly thirds, sixths, unisons,
8ve's, or tritones as your harmonic consonances. Inverted perfect 4th's/5th's
often imply harmonies that are not acceptable in the style.
Bach often used 2 countersubjects.
Example: Bach, WTC I, Fugue XII in fm
logical harmonic progression
much contrary motion (cm enclosed in box)
some similar motion (sm closed in box)
Most dissonances are passing. Only three are not (escape tone [esc], suspension
[sus], and lower neighbor [ln]). All dissonances are circled.
Countersubject is invertible: 3rds, 6ths & TT's (intervals are marked
above the staff)
Countersubject material contrasts Subject: sixteenth's, quarter's, and
rests in CS; mostly quarters in Subject.
