Monday
Monday's existence predates recorded history. The seven-day week emerged in ancient Babylon, with planetary associations that survive in the dies Lunae etymology. For approximately 4,000 years, Monday has maintained continuous operation without significant interruption, service outage, or existential crisis.
Projections suggest Monday will persist as long as human civilisation employs weekly temporal organisation. Even post-apocalyptic scenarios that eliminate other social structures would likely preserve some form of cyclical time-keeping, ensuring Monday's survival in perpetuity.
Ninja
The operational period of authentic ninja activity spans approximately five centuries, from the turbulent Sengoku period through the early Edo era. While this represents an impressive institutional lifespan by human standards, it constitutes merely one-eighth of Monday's documented existence.
Contemporary ninja practitioners are engaged in historical reconstruction rather than continuation of living tradition. The unbroken lineage claims of various ryu remain contested by academic historians, suggesting that the ninja's genuine longevity may be considerably shorter than popular accounts suggest.