I've often wondered why certain keys lend themselves to different moods in music -- B minor is the key of great drama, C major is for sun and simplicity, for example.
The New Scientist has published a little tidbit, "Songs in the Key of Life: What Makes Music Emotional?" that suggests the possibility that musical intervals may have a link to speech patterns. Major keys mirror excited speech. Minor keys mirror subdued speech. The researchers also suggest that these patterns cross cultures.
Here is an example of contrasting major and minor from my other favourite set of 24 Preludes & Fugues, the ones written by Dmitri Shostakovich. Sviatoslav Richter performs the A Major, followed by A Minor set from Op. 87. These were recorded in 1956.