Leo didn't stop being a materialist that day. But he upgraded his definition.

Leo was a materialist in the purest sense. Not just someone who liked nice shoes, but a true philosophical materialist: he believed only matter and energy existed. Consciousness was just brain chemistry. Love was just oxytocin. A sunset was just scattered light waves.

He realized that And meaning doesn't live in the atoms. It lives in the pattern the atoms make, and the story that pattern tells to a conscious mind.

The Resolution of Value