When you catch bugs early, you also get fewer compound bugs. Compound bugs are two separate bugs that interact: you trip going downstairs, and when you reach for the handrail it comes off in your hand.

Graham is arguing for the practical value of finding and fixing software defects as early as possible. Early bug discovery doesn’t merely reduce the total number of defects; it prevents “compound bugs,” where independent faults combine to create failures that are harder to diagnose and more damaging in effect. His staircase-and-handrail analogy captures how interacting problems can turn a minor mishap into a serious accident. In software, such interactions often produce misleading symptoms, multiply test cases, and increase the cost of repair because the system’s behavior becomes non-linear and unpredictable. The quote thus supports practices like rapid iteration, tight feedback loops, and continuous testing as ways to keep complexity from snowballing.