circle for dummies

Note that the cello note in the penultimate chord is a nonchord tone: it is a B but it should be an A, like at the beginning of the next measure. It resolves nicely upward in stepwise motion as part of the overall progression (observe the chords on the three consecutive beats starting with that one). Something similar happens at the end of the first phrase, with the viola starting on a chord tone (G) moving to a nonchord tone (A) that happens to be a chord tone in the next chord in the progression. This type of nonchord tone is called an anticipation. The next chord doesn't appear on the following beat because tension is nice.

Since you're reading the For Dummies version, the actual movement in the root of the chord is not obvious to you, so I've added a part explicitly marking it and highlighted where the root appears for each chord:



The viola has the root a lot because violas are great and should therefore have the most important part.