Music Theory

Modes 

We have been looking at the Key of A. Because of the starting point we have been looking at and its relationship to the third tone from the starting point we can tell we are working in A Major rather than A minor. This is because the third tone from the tonic note is two steps sharp. If it were minor then the third tone would be a half step flat of two steps sharp from the tonic note. So, Major means that the third tone is two steps sharp of the starting note and minor means the third tone is one in a half steps sharp of the starting note of the scale or chord you are playing in. As a side note, if someone says lets play the 2nd movement in C without specifying if its C major or C minor then by default it will be played in the Key of C Major.

In the Scales and Arpeggios section I talked about how you can play in the key of A while starting on a note other than A. Scales have different modes, or focus points. If you are playing in the Key of A we know the key of A belongs to the notes of A, B, C#, D, E, F# and G# and that this exact combination of notes belongs to no other key signature but the Key of A. We also know there are twelve notes in the musical alphabet so by this logic we know there are twelve keys, one for each note. Each of these twelve keys has its own unique combination of notes just as the key of A does. Knowing this, you can start on any note or focus a melody on any note in the Key of A and you will still be in the key of A. Depending on which note you focus on will determine which mode you are playing in and if it is major or minor. We know that the natural scale and its variations such as the harmonic minor and melodic minor scales each have seven notes per scale. Because the mode is determined by what note on a scale your focus note is, there can only be seven modes.

The seven modes in order are Ionian, Dorian, Phrygian, Lydian, Mixolydian, Aeolian and Locrian. We can determine for each of these modes if they are major or minor by where the third tone is located from that particular starting point. If you start with Ionian the third note is two steps sharp making Ionian a Major mode. The Ionian mode is the most common mode that a piece of music is played in. If you start with the Dorian mode you will see that that third tone from the Dorian starting point is one in a half steps sharp making Dorian a Minor Mode. Following this logic we know that Phrygian is Minor, Lydian is Major, Mixolydian is Major with a sharp fourth tone in relationship to its relative Major Ionian mode, Aeolian is Minor and Locrian is Minor with a flat second tone of its relative Major Ionian mode.

What I mean by relative is that you can pick any starting point of a scale, or mode of a scale, and see its other relative key signatures. For example, look at the tables below to see how modes intertwine with scales. If we are going to play something in the key of A Major Ionian mode then you can see from the table below that the relative Aeolian Minor is going to be the Key signature of F# Minor. F# Minor is the relative minor of A Major and A major is the relative major of F# Minor. Here is another side note, if someone says lets play a fugue in F# minor and they do not specify which mode then by default its the Aeolian mode because its the most common mode played of the minor modes. If a piece of music is to be played in A Major then its Ionian unless otherwise specified. Now if you want to get specific you can say that the relative Dorian Minor of A Ionian Major is the key of B dorian Minor. The point is, each key signature is going to have six other relative key signatures because there are seven modes total meaning that they are all the exact same notes, just a differing starting or focus point.

Natural Major Scale in A (A)

Modes	Ionian	Dorian	Phrygian	Lydian	Mixolydian	Aeolian	Locrian
Natural Scale, Key of A	A	B	C#	D	E	F#	G#

The Relative F# minor to A Major

Modes	Aeolian	Locrian	Ionian	Dorian	Phrygian	Lydian	Mixolydian
Natural Scale, Key of F# Minor	F#	G#	A	B	C#	D	E

Intervals 

An Interval is the distance between any two notes, starting with the lower note and then counting to the higher note. Intervals are broken into sizes: unisons,
2nd's, 3rd's, 4th's, 5th's, 6th's, and 7th's. Intervals can be described as being Major, Minor, Perfect, Augmented, or Diminished. Pick a scale and key signature such as A Minor and look at the third tone of that scale. This is a minor third interval. If you augment that third tone by one half step then you would have a major third interval based on the formula for a major scale. The same rules apply for the 2nd's, 6th's, and 7th's tones of a scale as well as 3rd's and they can all be found as major and minor depending on what key signature you are in or how far apart the higher note is from the lower note. Unisons, 4th's, 5th's and octaves are perfect intervals.