Begin challenging your own assumptions. Your assumptions are your windows on the world. Scrub them off every once in awhile, or the light won't come in.

Alda urges deliberate skepticism toward one’s own mental habits. “Assumptions” are compared to windows: they are necessary for seeing the world at all, but they also filter and distort what comes in. If we never “scrub” them—by testing beliefs against evidence, listening carefully to others, and revising our models—we gradually lose clarity and openness, mistaking accumulated grime for reality itself. The image also implies that insight is not merely acquiring new information; it is maintaining the conditions for perception. The quote aligns with Alda’s public emphasis on curiosity and communication: understanding improves when we notice what we’re taking for granted and actively clean up those unnoticed premises.