来自《耶鲁大学开放课程：聆听音乐 第13集 第13集》

• 
  
  and it's only in the eighteenth and nineteenth century
  直到十八至十九世纪
• 
  
  that we gradually shifted from an unequal keyboard
  我们才逐渐由不均调的键盘乐器
• 
  
  to an equally tuned keyboard.
  过度到了均调的键盘乐器
• 
  
  So Bach is kind of part of this transition
  所以巴赫正处在
• 
  
  to the equal-tuned keyboard.
  向均调键盘转型的时期
• 
  
  He was getting close to the equal temperament of the modern keyboard
  他开始逐渐熟悉均调的现代键盘
• 
  
  and that's why he called it the well-tuned keyboard,
  这就是为什么他称之为平均律键盘
• 
  
  and it--by tuning it this way,
  就调音而言
• 
  
  it allows you to modulate to all keys,
  这种键盘乐器可以转调到任何音
• 
  
  and that's what he did in this collection.
  巴赫在这部作品中就这么做了
• 
  
  He wrote a--two books,
  他有两本著作
• 
  
  one in seventeen-
  一本写于十七世纪