When Bach returned home, he found his wife already buried on July 7, 1720. The exact cause of death remains a mystery because she was healthy before Bach went to Carlsbad. There are a few theories that Maria Barbara might have gotten an infection or perhaps it was a complication of her pregnancy.
At any rate, this very unfortunate event left Bach in a situation when he had to find another wife rather quickly. 17 months after the death of Maria Barbara he married Anna Magdalena Wilcke. She raised her step-children along with her own.
Anna Magdalena was an accomplished singer and rather proficient keyboard player. To further her musical education, in 1722 and in 1725 Johann Sebastian compiled two collections of keyboard music for her which are rather similar - the first has only compositions of Johann Sebastian and the second also includes pieces of other composers of this period.
The bulk of the collections is music for keyboard - menuets, polonaises, marches, gavottes, rondeaux, chorales, sonatas, the French suites etc. with a few selections of vocal music as well.
The Notebooks for Anna Magdalena Bach gives us a glimpse into the domestic music making in the Bach family and provides a rather detailed picture of what Anna Magdalena played at home on the keyboard instruments the Bachs had at their disposal.
What is the value of these collections for today's organist or keyboardist?
The charming menuets, polonaises, marches and other dances are among the most-loved pieces by people who are relative beginners of any keyboard instrument. Their simple but artful musical language makes them perfect pieces for music-making at home.
Although composed almost 300 years ago this music never gets old or boring. I'm sure you are familiar with these 3 famous menuets (2 in G major and 1 in G minor). If you want, listen to them here, here and here.
Most keyboard music from this collection are dances for two or three parts divided into two halves and each of them is often repeated. For the repeats it's quite appropriate to add ornamentation or melodic figuration.
By the way, if you want to learn to play simple and beautiful menuets and other dances from the Notebooks of Anna Magdalena Bach, check out this course.