Over the years I have been a piano teacher I have had many people call or write me and ask me something like this: "I play by ear, or by chords, but lots of music doesn't have chord symbols written in -- how do I know what chord to play when?" "Our hymn book doesn't tell which chords to use -- how can I know what to play?" "I read music but don't have a clue what chords are being used. How can I know what they are?" What do you do if you want to play a song using chords instead of the written sheet music notes, but the song doesn't have any chord symbols printed -- symbols such as Cm7, G13, B+, D dim7, etc.? There's a logic behind every note written in music, & you can learn to understand that logic, and therefore understand music. If you can read music to some degree but don't "see through" the written music -- don't understand what you are seeing -- it is now very possible that you can put on your "chord glasses" that good "chord detectives" wear to see through all that mass of black printed notes on a white page of sheet music to quickly understand what chords are being used and the "family logic" behind it all.
The "family logic" is this: In every key there are certain chords which are organic to that key --"family members", so to speak. For example, in the key of F the 3 most used chords are F, Bb and C. In the key of G the most used chords are G, C, and D. In the key of Eb the most used chords are Eb, Ab, and Bb.
Do you see a pattern here? Chords are based on scales, and the chords which are used the most in any key are built on the 1st degree of the scale, the 4th degree of the scale, and the 5th degree of the scale. They are identified by using the Roman numerals I, IV, and V. So the most used chords in any key are the I chord, the IV chord, and the V chord.
They are the primary chords, and they are all major. They occur way more than other chords. The next most used chords are the ii chord, the iv chord, and the iii chord -- all minor chords. Just knowing these simple facts gives a musician a giant advantage when learning or playing a song. If he or she knows the most likely chords that are going to occur in a song, based on the key of the song, then they can scrape together other evidence quickly to build an air-tight case that they know the chords of that song. For example, let's take two musicians about to play from a piece of sheet music.
Both read music, but only one knows chords and music theory. The first musician looks at the notes and sees a Bb in the bass clef as the first note, a Eb in the bass clef in the second measure, a Bb in the 3rd measure, an F in the fourth measure, and so on. He can play what he sees, but nothing else, because he doesn't grasp the fact that the first few measure have given away the fact that the primary chords have been outlined.
The second musician looks at the same music, but with "X-ray eyes". He sees through the same notes into the chord structure behind the scenes. The first musician is tied to the written music and limited to the notes printed on the sheet music, while the second musician has the best of both worlds: he can read the music and play it as it is written, but he can also add chords and fills and come out with a much bigger, more interesting arrangement than the first musician. The benefits of becoming a chord detective are many: It allows a musician to immediately identify what key a song is in. It allows a musician to know POSITIVELY which chords are most likely to occur in each song. It allows a musician to look at the first measure and the last measure and immediately know the harmonic form of any song.
Plus: It works in any key -- major or minor. It works with any kind of hymn or gospel song. It works by releasing a musician from being "tied to the written music".
It works by allowing a musician to add chords of his or her own. The bottom line is this: knowing chords and music theory allows a "chord detective" to develop "see through eyes" that immediately perceive the structure of a song and then allow that musician to use both the written score and any fillers or improvisations he or she desires to add to a song.
For more information on becoming a "Chord Detective", please go to "How To Become a "Chord Detective" & See Through The Notes Into The Music!"