I think I'm figuring out the mixed modes thing. For Locke, a "mixed mode" refers to abstraction, words that attempt to represent concepts not found in the natural world. Or at least, there's not a one-to-one, sign-to-signifier relationship in the natural world for concepts like good or bad.

Locke identifies a similar problem in his own writing, but unlike Nietzsche, refuses to address it further: "Words having naturally no signification, the idea which each stands for must be learned and retained, by those who would exchange thoughts, and hold intelligible discourse with others...Those [words] which are not intelligible at all, such as names standing for any simple ideas which another has not organs of faculties to attain; as the names of colours to a blind man, or sounds to a deaf man need not here be mentioned...for if we examine them, we shall find that the names of mixed modes are most liable to doubtfulness and imperfection."

Although Locke doesn't delve much deeper into this, I do like how he notes that some words are used to describe "mixed modes" like music and color. Nietzsche addresses this concept below, saying that although a man might be deaf, he can still "feel" music (via vibrations) and therefore might understand sound in a way that is divergent from the conventional manner. I'm also reminded of Rickert's piece, in which he noted that Homer could never identify the color "blue" as we understand it today, instead calling the color of the sea "purple" or "wine red."

"Mixed modes" comes up quite a few times throughout this excerpt, so I went looking for a definition...

Here's a breakdown of "complex ideas" that might be helpful with some of the terminology used throughout this excerpt (modes, substances, and relations).

Also, when I got to Book III, 18-20, I kind of wished those were earlier. They give a quick (and maybe useful?) explanation of simple ideas, simple modes, mixed modes, and substances.