Gradus Chapter 2

Front 1

note one

Back 1

first note on downbeat MUST be consonant

second note on upbeat may be dissonant if it moves from the previous note to the next stepwise

therefore; If the upbeat note is a skip it must be consonant

Front 2

note two

Back 2

dissonance may not occur except as a passing note between two notes a third apart

follow the rules of the First Species

Front 3

exceptions

Back 3

The next to last measure should have a 5th followed by a Major 6th when the cantus firmus is in the lower voice

The next to last measure should have a 5th followed by a minor 3rd if the cantus firmus is in the upper voice

Front 4

note three

Back 4

a skip of a third cannot prevent a forbidden succession of two fifths or two octaves in direct motion, but a fourth can (this also sometimes applies to imperfect consonance to perfect consonance leading in direct motion- usually an error, but the fourth can cancel the error out)

It is allowed to use a half rest in place of the first note of the counterpoint; encourages the impression of independence of voices

If voices become so close that further movement doesn't allow contrary motion- it is permitted to use a skip of a minor 6th or octave

Front 5

note four

Back 5

if the mode suggests a dissonance in the mandatory fifth in the penultimate measure, alter the interval (eg, a 6th)

in ternary time- apply similar rules, but note that if moving by step, the middle note may be dissonant; but if moving by skip then all three must be consonant