Eighth, Eighth, Quarter, Eighth, Eighth, Quarter
These six notes have been boxed in blue.
The second group of six is a diatonic transposition of the first group, down a second.
The first two-measure pattern takes us from a C chord (tonic) to a G chord (dominant), the second, from a G7 chord (dominant) back to a C chord (tonic). If we describe the tonic chord sounding like "home," then the dominant chord sounds "away and anxious to return home."
This movement from the tonic to the dominant and back again helps guide the ear in dividing the notes of the first four measures into two phrases: "home-away" and "away-home."
These two two-measure patterns are followed by a long four-measure phrase outlining a D7 chord and leading to a G chord. This four measure phrase is an extended "away" phrase that harmonically leads back to the C chord at the beginning.
Here is a grapical representation. In these graphs, blue groups are short elements, red groups are long elements, and gray groups are of no concern. The x-axis is time and the y-axis is pitch.
Thus the first eight measures have been divided as
| Short (2 measures) | Short (2 measures) | Long (4 measures) |