Though the key signature of Release in the anthology indicates that it is in C minor, it doesn't really fit into these classical definitions of major or minor.

Listen to Scarborough Fair, a famous folk tune. Its melody also doesn't fit into a major or minor tonality. There are other scales in music which are called modes. These have been used in folk music for centuries and perhaps hold a more plaintive and traditional tonal quality.

The first line of this song (0'15) could be in E minor as it follows the scale of the minor key. But in the second line (0'23) the use of the D natural and the C# scupper this and show that the music is actually in the Dorian mode, which resembles a minor scale with a flattened 7th and a sharpened 6th.

You can play the Dorian mode on a keyboard by playing the white keys from D to D.

There are times in Release, as discussed in the section on Harmony, where C minor triads are played, and this suggests that the music is in C minor. However, without any cadences you can't really go any further with this theory.

Looking at the notation from the vocal melody below, it's clear to see that there is a B flat used which suggests that Release is also modal. However, there are A flats sung later in the melody which means that this song doesn't fit the dorian mode, like Scarborough Fair. It is better to describe it as being in the Aeolian mode, which is sometimes called the natural minor.