So think of this as a kind of series of boxcars

想象一下这就好像
on a railroad train or something like that--

火车的一系列车厢一样
units more or less the same size,

它们都差不多大小
but each of those boxcars is going to

但每节车厢
look a little bit different as it goes by

在开过时都有不同
because it might have a little different logo on it

可能车厢上贴有不同的标志
or a little bit of different ornamental material on it.

或是不同的装饰材料
All right.So we're going to--let's see.

好我们继续
For time,maybe I'll--we'll not do the Ives.

好像时间不允许我们讲艾夫斯的音乐了
We were going to-- well,maybe we will have a little bit of Ives.

我们将…也许我们还有时间留给艾夫斯
Theme and variations: again,

我们开始讲主题与变奏
it goes all the way back to the Middle Ages and it--

这又是一种源自中世纪的音乐形式