These three events (His Birth, His Enlightenment, and His Passing away) took place on the same day and month, but difference in year. The importance of Visakha Puja Day As mentioned that Visakha Puja Day is the Day of the Buddha. When considering in this point, we have seen clearly that the Birth of the Buddha was also the Origin of Buddhism. Because the Buddha was born, attained enlightenment, and then established Buddhism. So the Birth of the Buddha and the Origin of Buddhism were very important in the history of humankind. The Birth of the Buddha, the Enlightenment of the Buddha, and Last of all, Visakha Puja Day is the day which the Lord Buddha attained Nirvana or Parinibbana.
The Lord Buddha gave us the final advice "All conditioned things undergo changes.
Decay is a normal process. All of you must not be reckless.
You must hurry to find your refuge."