The music of the sixteenth century is based upon the so-called ecclesiastical modes, a system of modes that existed in the music of western Europe from the origin of the Latin Church and dominated music until the seventeenth century, when the transition to our major-minor system, long under way, finally began to prevail. The fundamental principle of organization, which was called oktoechos, was founded upon a system of 8 modes.
Originally only four modes were actually used. These were designatedwith the Greek numbers Protus (the first), Deuterus (the second), Tritus (the third), and Tetrardus (the fourth). Each of these modes was later divided into two forms, a lower called plagal (Derived), and a higher called the Authentic form. In spite of having different ranges ( the beginning tone of the plagal scale was always a fourth below that of the corresponding authentic), both modes have the same final.
The system of the 8 modes seems to have appeared as early as the time of Pope Gregory the Great, who ruled from 590 to 604. Currently there is a 12 mode system used to write Counterpoint. Ok, enough with the History lesson( Dispite the fact that there is alot more to tell). So how do we write a Counterpoint? Well first we must understand a few things.
What is cantus firmus?
A Cantus Firmus is a fixed melody one phrase in length and terminated by a melodic cadence. It is what we write the counterpoint against.
What is a cadence?
Cadences are like puntuation at the ends of phrases. In a single line, cadences are usually made by a descending step.
What are Consonances?
Consonances are Intervals, They are divided into two groups Perfect: Unison, Fifth, Octave. Imperfect: Third, Sixth.
What are Dissonances?
Dissonances are The intervals of a second, fourth, augmented fourth, diminished fifth, and seventh.
What is a compound interval?
Any interval larger than an octave.
The Rules of counterpoint relate the vertical (or simultaneous) intervals to the melodic (or linear) intervals by which they are approached.
What is Voice Leading?
Voice leading is the relationship between the melodic and the vertical dimensions
There are basically two types of Melodic motion: by skip (disjunct) and by step (conjunct, or stepwise). There are four types of motion between two parts: Parallel, in which both voices move in the same direction by the same interval. Similar, in which both voices move in the same direction but by different intervals. Oblique, in which one voice stays the same while the other ascends or descends. Contrary, both voices move by different interals in different directions.
If you were to study Counterpoint in school you would learn about what we call "Hard rules" and "Soft Rules."
Hard Rules: Rules that cannot be broken under any circumstances. Most hard rules are based on Contrapuntal principles.
Soft Rules: Are more a matter of taste.
Hard rules:
Use only natural notes and bb. When the signiture is Bb. Eb may be used in the same way as Bb.
Skips of augmented and diminished intervals, and skips larger than sixth are prohibited (except that of the octave). This means that no chromatic motions are allowed, no leaps of augmented fourths (Tritones) or diminished fifths, no augmented seconds, diminished fourths etc. Skips of a sixth must be used sparingly.
Outlines of an augmented fourth are forbidden, and a diminished fifth outlin must be completely filled in and followed by a step in the opposite direction. An outline is the interval from the temporary high point in a line to the next temporary low point, or vice-versa.
Begin and end with perfect consonances between the two parts. This means you may begin at the unison, fifth or octave ( And rarely, a twelfth) above or below.
All downbeats must be consonant. All perfect intervals must be approached by contrary or oblique motion. Repeated notes in the counterpoint may not occur against repeated notes in the cf. Counterpoint may run parallel to the cf for four noutes maximum. Skips must account for less than half the melodic motions. Direct repetition of the whole contrapuntal combination (two or more simultaneiteis) is forbidden, and only two sequential repetitions are allowed. Ok, that's it for now. Some time when I get around to it, I'll talk about "Soft Rules" and get to examples in writing a proper counterpoint. For now here is a correct CP and CF to study.
H H H H H H H H H H H H H H H H H H H H H H H H H H H H W
|----------------------------------------------------------------|
|-------------1--------------------------------------------------|
|-----2-5-4-2---4---2-2-2-3-2---2-----------------2-----2--------|
|-5-5-------------5-----------5---3-5-5-5-5-2-5-5---3-5---5------|
|----------------------------------------------------------------|
|----------------------------------------------------------------|
| |
| H H H H H H H H H H H H H H H H H H H H H H H H H H H H Q W |
|----------------------------------------------------------------|
|-5-2-0-----0-2-2-2-0---3-5-3-2-0-0---------------------5-4-5----|
|-------3-------------3-------------3-2-3---0-2-3-3-5-3----------|
|---------3-------------------------------3----------------------|
/ my profile 
