The script began as a single alphabet. I had become very dissatisfied with my handwriting—it was uneven, varying in slant, thickness, and form. So I decided to come up with a single, unified alphabet to teach myself. I decided to come up with a set of letterforms and practice them so I wrote consistently.
Early on I decided to make the alphabet unicase—not only did I prefer the more solid appearance, but I appreciated the simplicity. I knew that word shape, as determined by ascenders and descenders, was crucial for readability, so in nearly every instance I chose for my one case the form of the letter that went above the x-height or below the baseline. I was already, I guess, being a little bit daring, or idiosyncratic; at this point already I was doing things like eliminating the bottom stroke in the letter k.
After the letters, the notion of abbreviations for common digraphs, ligatures, or words came gradually. It had its origin, specifically, in the ampersand, which I had disliked writing for a very long time—the ampersand '&' is hell for nearly anybody to write by hand!
I figured I might as well come up with—or choose from history—a glyph more suited to handwriting. I found it in an old but not entirely obsolete ligature. Once I integrated that into the alphabet, it was more convenient and attractive than what had come before.
From there followed some of the double letters which I found tiresome to write: ee, ff, et cetera. I went searching for ligatures that would translate well into handwriting; for more historical models like with the ampersand. In fact, I found relatively few—there aren't a lot of conventional ways of writing doubled-up letters in English. But in my reading I came onto the idea of scribal abbreviations. It was at that point that I started to include those in the system—drawing some from the medieval Latin originals, or creating new ones myself.