Color has an objective structure and a subjective response, and both need training

Itten's foundational claim is that color operates on two levels simultaneously, and most people only ever develop one of them. The objective level concerns measurable relationships — which hues sit opposite each other, which combinations increase or cancel each other's intensity, how a color shifts depending on what surrounds it. The subjective level concerns the private emotional and associative charge a color carries for a given viewer, shaped by temperament, memory, and culture.

He insists neither level alone is sufficient for serious work. An artist who only feels color intuitively will produce inconsistent, unrepeatable results; an artist who only knows the rules will produce technically correct but lifeless compositions. His teaching method, and this book, exist to develop both faculties side by side: structured exercises to sharpen perception of objective relationships, paired with reflective practice to notice and articulate one's own emotional responses to specific palettes.

Takeaway: don't trust your gut alone, and don't trust the wheel alone — train both, and check one against the other.