But high in his stronghold Aeolus wields his scepter, soothing their passions, tempering their fury. Should he fail, surely they’d blow the world away, hurling the land and deep sky through space. Virgil, Aeneid, translated by Fagles, 49.
These are wonderful images of the Greek mythological figure, Aeolus, keeper of the winds, who harboured them a cave. If he chose to loose the winds, all existence could blow away. With his control of the winds he could bring fortune or disaster to ships at sea.
Once, I helped a friend move his harp from a performance space. It was a warm spring night in Kansas with a strong south wind funneled between two buildings where we were loading. We set the harp down briefly and all the strings began to resonate in the wind, creating a lovely pan-tonal sound that oscillated with fluctuations of the wind. Aeolian harps function in such a manner, resonating in outdoor spaces in the wind.
When I first composed for the harp, I spent my research time reading Carlos Salzedo’s “Modern Study of the Harp.” He explains much notation specific to extended techniques for the instrument.
There are seven tones (or “pitch classes”) possible at any time on the harp. By manipulating a series of pedals, the player can change each pitch class from flat, to natural, to sharp (e.g., D-flat, D-natural, D-sharp). A composer can’t write a D-sharp and a D-natural at the same time for the harp, but can compose an E-flat (which is the same sounding pitch as D-sharp) and D. Two different designations for the same sounding pitch are said to be "enharmonic" spellings. Hence A-sharp is the same as B-flat, F-sharp the same as G-flat, etc.
When composing for the harp, one must work within the limitations of the tuning. Strangely I find the limitations of any instrument liberating. There are things one can and cannot do with an instrument; notes that can and cannot be realized. So choices one makes are focused from the physical possibilities of an instrument. For some reason, these limitations suggest and enable creative directions through restriction. To paraphrase a popular aphorism: When one path is closed (in a creative endeavor), another opens up.