All our knowledge has its origins in our perceptions.

Everything you know arrived through senses with known limits, filtered by attention that was already looking for something. That does not make knowledge worthless, but the raw material was never neutral, and two careful people can watch the same event and store different facts. What you call obvious is often just what you were positioned to see.

When you feel certain about something, trace it back to how it reached you. Did you observe it, hear it, or infer it from a single example? Returning to the source occasionally is cheaper than defending a conclusion built on one glance.