What is three chord (C, F and G7)?

Pythagoras found that simple 1/2, 1/3 or 3/4 length of string or weight of metal gives very good harmony with the original one. This is the origin of harmony in music, according to Howard Goodall. When we think C key (original) is, 1/2 is also C octave below. And 1/3 and 2/3 are G, 3/4 is F.

image post

This evidence is well described in this circle of 5th below. 2/3 of C string is G. 2/3 of G string is D.......

free image hosting

F and G give best harmony with C. Hence we use them as member of three chord in key of C.

We can see 1/2 (C on the 3rd line), 3/4 (F) and 2/3 points (from saddle) on the fretboard.

image free hosting

Huh. Never thought of it like this.

This beginner needs more explanation.

I like the visuals here. Well done!

Thanks for sharing!

There are 7 diatonic chords in the key of C

upload photo

F and G harmonize with C most in the 7. Hence they are often used for framework of the song as three chord in the key of C.

Now I get it, thanks.

@Hippie Guy
I've just finished to read "Big Bangs: The Story of Five Discoveries that Changed Musical History" by Howard Goodall. It is very interesting book. I really did not know the meaning of circle of 5th ever before.

@padlin
Thank you for asking. I've forgot to write most important thing. ^^

@bolli
I always appreciate your posts including strings experiments.

Impressive. I never thought about it in that way.