Consonances and Dissonances - Insanguine's Partimento Rules Book P. 2

CONSONANCES & DISSONANCES

There are four consonances, the 3rd, 5th, 6th, and 8ve, two of which are called “perfect” and two “imperfect.”

The perfect ones are the 5th and 8va, and they are called perfect because one can neither alter nor diminish them.

The imperfect ones are the 3rd and 6th, and they are called imperfect because one can alter or diminish them, that is, one can make them bigger or smaller.

There are also four dissonances, the 2nd, 4th, 7th, and 9th, and these cannot be used unless they are prepared and resolved to one of the consonances.