Authentic and Plagal Cadences in Music

Cadences move step-wise through the Circle of Fifths and are a big part of the Western music culture. Authentic means that we move counter-clockwise, plagal refers to moving clockwise. As long as you don't skip any step in the Circle of Fifths, you'll create nice-sounding chord progressions.

Authentic Cadences

Before we go into some actual music, let's look at how the tones move through the Circle of Fifths in the authentic direction, which is counter-clockwise. You see that the distance between all the tones remains the same: five chromatic steps up. We call the Circle of Fifths a Root Cycle 5 (or RC5). If we want to follow the authentic way, the direction of the stacked notes is ascending.

Let's look at the notation of the RC5 in the bass clef. Sometimes, the notes create a diatonic perfect 5th (that's seven chromatic steps), and sometimes, they make a diatonic perfect 4th (that's five chromatic steps) — the reason why we did this is that we wanted to keep all the tones in one octave. We want to use those tones as roots later.

However, I want to shift your attention from the physical movement to the "Harmonic Weight," which is the shortest distance between two neighboring notes in the bass. With the Circle of Fifths, the shortest distance between two notes is always five chromatic steps, either up or down!

So, in authentic cadences, the harmonic weight always goes five chromatic steps up! Please don't confuse the physical movement with the harmonic weight! They are two separate things. For our explorations, we need to focus on the harmonic weight.

It's pretty abstract if no chord structures show up above the roots, so let's add major triads on top. Please note that we don't write in a key in Interval Theory! Every root tone creates its unique temporary tonal center. This idea goes contrary to what the Diatonic system suggests, but it opens up a whole new world of opportunities, as you'll see and hear in the musical demonstration below.

The result is very musical already, but that's just the beginning. Let's add more variety and make every other chord into a minor triad. This gives us even more options and inspiration to create a beautiful composition at the end of this article. This all follows 100% technique and doesn't depend on your creativity, but don't worry; we'll sprinkle in many creative things as we proceed.

You can switch from major to minor to your liking and at any point. We just followed a simple pattern for now, and you can take this as inspiration to develop your own ideas. Take a bit of time and get inspired by what you hear. Give yourself some options and colors to work with so that you save lots of time later when you go into the sketch and the orchestration.

Plagal Cadences

Let's look at the plagal side next. The only difference between authentic and plagal cadences is the direction of the harmonic weight in the bass register. On the authentic side, we went up by five chromatic steps, remember? Now, we go down by the same distance. As a result, we move clockwise through the Circle of Fifths.

Although it's logical, the following might be new to you: Authentic and plagal are reflections of one another. Why is this good to know? - Because it's the entry into Negative Harmony and a new world of sounds and options.

Everything we just did on the authentic side can also be applied to plagal. See how the harmonic weight changed the direction?

It might not seem that important to you, but be sure you know the harmonic weight between two neighboring root tones! This knowledge will serve you well, especially when we use other composition techniques like extended roots, more complex chords, or substitute voice-leading!

You can switch between major and minor triads on top of your cadences. That's part of the freedom of not writing in a musical key. However, put your attention to the movement in the lower register. Make sure that it goes either five up or down. This alone will give you very musical results that you can instantly turn into good-sounding music.

I'm a huge fan of triads. They connect to many musical places, such as Polytonality, Negative Harmony, Equivalents, Pentatonic, and more. Furthermore, they are easy to handle and sound great! Here are the plagal cadences with alternating major and minor triads on top.

Chord Tone Substitutions & Creating a Sketch

A great way to add even more color and variation is by using substitute tones. Start simple and use basic triad structures first before you start to substitute. Actually, this is a general guideline that will make your compositional life easy: Always build from simple to complex, not the other way around!

Here are the most common scale-tone substitutions for triads that sound great and you should try:

Those substitutions can also work nicely as passing tones to add more movement to your parts. In the example below, I go through the authentic cadence (the RC5 ascending) with alternating major and minor triads and add some line movement on top. Look at the bass and the colored notes above, and you'll spot the original authentic cadence.

I understand that it might take some time for you to figure out what notes to pick as substitutions. The secret to developing speed in the writing process lies in the order of the steps:

1. Start simple by writing out your root tones first. 
2. Add the major and minor triads above.
3. Use the substitutions.

It's best to bring in line movement later and in a dedicated step - don't mix those steps.

Now, the time has come. We want to take this exact sketch and turn it into a full-blown orchestral piece of music. Sounds good? ... let's do this!

Marc's choice of orchestration is a powerful demonstration of the concepts we teach inside the Music Interval Theory Academy, including...

The orchestration is usually like a puzzle, and there are many correct ways to solve it. You must commit to the first puzzle piece to build around that starting point. And the truth is that there are smart starting points that lead to great results much quicker than fiddling around for hours. Again, it comes down to being organized and having a plan of action!

Conclusion & Summary

Authentic and plagal cadences are clichées but still very powerful in composition. Since everybody uses the Circle of Fifths (for good reasons), finding something that sets you apart is good advice.

Following the Circle of Fifths step by step will give you some musical material to start with. Next, use composition techniques, like interval theory, and combine all of these with your unique taste. Here's a quick summary of what we've covered: