Chord progressions by major and minor second are a common feature of all tonal styles. They can appear at any points in the phrase, as the example below shows.
This example contains more progressions by a second than you might usually expect to find in one phrase. When trying to write in the style of Bach (and most other tonal composers) you have to be careful to avoid parallel fifths when using this sort of of progression. The page on IV-V progressions gives an example of this potential problem.
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