Musical Composition, Theory and Songwriting/Bach


I played the C major Prelude on the piano and now I am analysing this prelude. In what way should one analyse such a prelude? I read that the second chord (second bar) has a ii2 chord. What exactly does that mean? This prelude also contain some accidentals even though it's in C major. Could you explain? Will the circle of fifths be of any help? Is this prelude just Bach (or whoever wrote it) just having fun with some chords or did he follow some rules for writing preludes?

Hi Hank,

Thanks for getting in touch. I assume that you are refering to the well-known Bach C Major Prelude that is made up mostly of semiquavers (16th notes) in the right hand part. There are several different ways to analyse a musical piece. You can for example look at the harmonic patterns, the use of rhythm, the use of dynamics, the use of contrast and so on. However, in this Bach piece it is relatively straight forward because (f I remember correctly) the rhythm is the same all the way through and there are no indications of dynamics (i.e. loudness or softness). If there are, they've been added by an editor and not by Bach huimself. So we're left more-or-less with the harmonic analysis which involves looking at the chords and how they are used.

To save us both a lot of time, it would be a good idea for you to look around the web for some pages about basic harmony. That will begin to answer your questions. Let me try to very briefly answer your specific questions to give you a start.

In the 1st bar, it is C major harmony because all the notes of the C major chord are there. This is usually indicated by a 1 (one) chord written in Roman numbers like this "I". Each note of the scale (regardless of key) can be thus numbered so for example in the key of C the chord of F could be shown as a IV, because F is the fourth note of the C major scale. Likewise a G chord could be shown as a V. It gets somewhat more complicated than this. In the second bar, the ii2 expression is rather strange. This chord is more usually described as either Dm/C or sometimes ii7/d. This might not mean anything to you so I suggest that you go here:

to find out about basic harmony.

Many pieces in C major contain additional notes which are "foreign" to the key. They are called "accidentals" and add colour and interest to the music. So in C major you are very likely to find extra sharps and flats appearing. Another reason is that sometime the music mmoves briefly into another key. Although tehnically this would require a new key signature, most composers don't bother and just add sharps and flats as necessary. I don't think the circle of fifths will be much help to you because it merely shows the relationship between one key and another.

I like your idea of "having fun with some chords" which is probably what it boils down to, but there are various conventions in harmony that have emerged over the years, tried and tested patterns of chords that seem to work well. They are not "rules" as such, although you will often hear about "rules of harmony". They are just conventions which have gradually developed over the years. Bach was certainly aware of them and so are most composers and arrangers today.

When you have read a bit more about harmony on the above web page, feel free to get back to me if you think I can help. Good luck with your studies!

Best wishes


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Dr Colin


I can answer questions from students of "classical" composing, arranging, notation problems and music theory, writing for instruments and voice and writing music for education. I can answer questions about orchestration but I do not cover questions about pop or rock music, pop song writing or electronic music.

I taught for many years in UK up to "A" level theory and composition. I have spent many years in music education, initially (like everyone else) as a teacher. Then I moved on to advisory work (teaching teachers!) and also lectured, giving many workshops for teachers in developing music education skills and techniques. For a time I worked as a teacher-lecturer at London University's Institute of Education and eventually worked full-time as a Music Education Adviser to schools in part of London, offering advice on music education and curriculum development.


I started composing music at the age 14 (it was mostly rubbish, since you asked) and now have a large number of compositions to credit as well as many publications, especially for instrumental music and choral music. I have also written several acclaimed works for large orchestra and choir. My work has been published particularly in the UK (under different names)(notably by Boosey & Hawkes, Novello, and Schott) but also in the USA and the Netherlands.

My music for elementary players (several publications) has been performed and broadcast worldwide. I am now retired from my previous job as Music Education Adviser. These days I spend most of my time composing and arranging. I am currently working on instrumental arrangements of world national anthems for my National Anthems website and also completing a suite of very easy piano solos and duets for elementary players. For many years I have used the music program "Finale" for all my music writing activities.

International Society for Music Education; Fellow of the Royal Society of Arts.

"The Times" Educational Supplement; "Hi-Fi News and Record Review". For several years, I used to write for many of the state music education periodicals in the US and I also wrote several influential articles on instrumental music teaching for "Music Teacher" magazine in the UK. (UK).

PhD(Hons); MA(Hons); FLCM (compositon) ARCM, LMusTCL,(music diplomas)

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