Happy Yalda Night!
Yalda celebrates the winter solstice, as the days become longer and the nights shorter in the northern hemisphere. In that sense, it spiritually celebrates the rebirth of the Sun Goddess Mithra (wall carving photo left). A deeply rooted ceremony, the annual observation of the winter solstice by Iranians and others signifies that man has known for thousands of years that THE SUN birthed all plant and animal life on our planet. Moreover, ancient Iranians' ability to accurately predict the solstice and to know key moments on the solar calendar is directly related to mankind's survival, prosperity, ability to plan for the future, and ability to conceive of time. Yalda is so old that it even predates Zoroastrianism-- Iran's religion prior to the Arab invasion and largely forced conversions to Islam-- and is really a Mithraic holiday that would soon be adopted by Zoroastrians.
While Iran's Zoroastrian faith placed the greatest emphasis on fire and light, traditional reverence for light was and remains common and extends well beyond the Iranian plateau. Jesus Christ, of course, is referred to as "the Light of the World", and the Scandinavian festival of St. Lucia similarly symbolizes bringing the "Light of Christianity" into the world. (Those interested in learning more about the deep religious influence Zoroastrian Iran had on the Holy Roman Empire should look up the Cult of Mithras)
Sometimes, it is difficult to conceive of a pre-modern, pre-industrial and pre-agricultural world and all its challenges to human survival. Cultivating a monumentalist relationship to history rooted in one's own heritage and longstanding annual rituals like Yalda is one way to spiritually surpass time and space and reconnect with previous epochs, in this case, one in which light was so rare and crucial as to be worshipped.
Regardless of humanity's divergent cultures and mutually-exclusive religious traditions, there is a common source of energy that binds us all to a shared past and a shared imaginative and interstellar future. While there are some 6,500 distinct languages with their own words for 'light', there is only ONE SUN that birthed us all. Happy Yalda!