Locrian is the darkest of all the modes, and it is just about impossible to write something that starts and ends with this mode. It sounds unfinished, incomplete. It leaves you hanging. So in this piece I start in Locrian, then come back to it almost at the end. Locrian asks a question, which begs an answer. Locrian is terrible for ending a piece.
This is actually mostly about Aeolian, also called natural minor.
At first I had no idea what kind of pictures to use for this music. But it occurred to me that minor, in general, is perceived as more serious, more somber and a bit darker – not necessarily dark, just darker than major. For the same reason, major is generally associated with something that is lighter in mood.
I tend to associate darker and lighter colors with music.
With that in mind, I very carefully picked pictures that are dark blue for the Aeolian sound as I move through different keys. I start in A Aeolian, move to D Aeolian, then move to G Aeolian. I am essentially using the circle of fifths for modulating. To get back to my original key, I move to an E7b5 chord, a true dominant 7, to take me back to A Aeolian again.
From that point I simply lengthen things as we often do at the end of a composition and then return to the same Locrian idea that is at the beginning to bind the whole thing together. To complete the whole thing I simply move to an A minor feel, or A Aeolian if you wish, to end in the same key that I started.