I want to know the answer to the following question:
What system of temperaments was common during Bach's time?
All the background I'm provided with is that "Although Bach did not use equal temperament, as a modern piano is generally tuned, changes in the temperaments from the meantone system, common at the time, to various temperaments that made modulation between all keys musically acceptable, made possible Bach's Well-Tempered Clavier.". Is that enough to answer the question?