Explaining music secrets to an extra terrestrial

If an extra terrestrial comes to earth and would like to know how music is composed in a few sentences what would one tell her, him, it?


How is music composed, made, how does it work? How do we know what to play with the left hand or the right hand which usually plays notes together or harmony?


This had been discussed yesterday with Vicky...


1 left hand usually plays bass. Bass is one note at a time. Melody is also one note at a time. Harmony or chords is many notes together.


2 almost all music is made with just 7 notes. But we must know what the particular scale or key we use for a song or symphony as this defines which of the seven notes are flat or sharp.


3 everything is referenced to the bass and to the white or natural seven notes. Bass comes from the Hellenic word βασις which means foundation [Bach].


4 the music game is played as follows. The composer chooses one bass note at a time. Then by using the simple rule or 1, 3, 5 , 7, 9, 11, 13 notes above the particular bass in a particular instant of the song or symphony we know what we can use for harmony.
For example if bass is E we can use for the right hand G, B, D, F, A, C.
These are the ingredients but we do not use them all as it is like a woman wearing all her jewelry at the same time.
For example Nights in White Satin - Moody Blues uses with bass E the default code which is 1 3 5. This means bass E with G and B and (E).
The same song for bass D uses code 69 (six nine) ie D69. This means we use the 6th scale note above bass and the 9th scale note above bass and add the 3rd scale note above bass [Bach]. So it is D bass and F B E.


5 but how on earth D69 comes about?
The human ear brain likes to have disconant intervals which respect to bass prepared in advance with a previous bass were they are consonant. So then the disconant intervals sounds fantastic (with the 3rd added, [Bach]).
So Nights is White Satin is
E bass and G B E
D bass and F B E resolved to F B D or 3 5
E bass and G B E
(Remember F is sharp as the key or scale is E minor otherwise all magic is lost.


6 the principle of least change in music suggests us to use the notes of harmony in such a way that the right hand makes the least change between chord notes.
On above example all the right hand does is change form playing G to playing F sharp and the other notes remain the same.
This invertion not only makes life on earth easy but it sounds fantastic too making otherwise disconant intervals to be prepared for the human brain and sounding paradise on earth.


Reference:


Bach Bass Rules - Bach, Niedt - PDF



PS
Where do the seven notes come from? See adjacent post.