In Roman Catholic Christianity, today is a holy day of obligation, celebrating the Immaculate Conception of the Blessed Virgin Mary. According to this doctrine, Mary was conceived without original sin. The doctrine has long been held but was finally defined dogmatically in 1854 by Pope Pius IX.
Today is also Bodhi Day, a Buddhist holiday commemorating the attainment of enlightenment by the Buddha, Siddhartha Gautama. After years of seeking enlightenment (bodhi) he found it through meditation, awakening to the truth after 49 days of meditation.