What does Paul Samuelson's quote funeral by funeral theory advances mean?

Paul Samuelson's "funeral by funeral" theory suggests that economic theories and policies can often only be fully understood or implemented after the proponents of older ideas pass away. This reflects the notion that entrenched beliefs can hinder the acceptance of new theories, as existing paradigms often dominate until those who champion them are no longer influential. Essentially, it underscores the slow evolution of economic thought and the challenges of overcoming established doctrines.