Bach is good for the soul as well as for the body, and I recommend that you never lose touch with him. Which is the best edition would be hard to say, but I have found the Peters edition to be very good.
Bach's Preludes and Fugues
What is the plan of a "Fugue," how does it differ from an "Invention" and "Prelude," and what is the purpose of studying the pieces so named by Bach?
The explanation of the plan of a Fugue would exceed by far the limits of the space at my disposal. It would require a text-book, of which there are many to be found in every good music store. The Fugue is the most legitimate representation of true polyphony. Its difference from an Invention is expressed in the two names. A Fugue (fuga, flight) is the flight of one musical thought through many voices or parts, subject to strict rules, while an Invention is an accumulation of thoughts moving with absolute freedom. The definition of Prelude, as something which intentionally precedes and fittingly introduces a main action, fits the musical Prelude perfectly; especially in the case of Bach. The purpose of all these forms is that of all good music-making, namely, the purification and development of good taste in music.
As to the Bach Fugues
Of the Bach fugues do you consider the C sharp major difficult to memorize, or do you advise the use of the D flat arrangement instead?
Such little differences have never bothered me, and I can therefore hardly answer your question definitely. It has been frequently observed—though never explained—that to many people it comes easier to read music in D flat than in C sharp. Hence, if you prefer the D flat edition it will reduce the difficulty for you. Possibly this more accessible version may aid you optically or visually in your work of memorizing.
[BEETHOVEN]
Order of Studying Beethoven's Sonatas
I am just beginning to reach an intelligent interpretation of Beethoven's music. Now, in what order should the Sonatas be studied?