This sacred day [Naw-Ruz] when the sun illumines equally the whole earth is called the equinox and the equinox is the symbol of the divine messenger. The sun of truth rises on the horizon of divine mercy and sends forth its rays on all. This is the beginning of the spring. When the sun appears at the equinox it causes a movement in all living things. The mineral world is set in motion, plants begin to sprout, the desert is changed into a prairie, trees bud and every living thing responds, including the bodies of animals and men.
The rising of the sun at the equinox is the symbol of life and the human reality is revivified; our thoughts are transformed and our intelligence is quickened. The sun of truth bestows eternal life, just as the solar sun is the cause of terrestrial life. - - 'Abdu'l-Baha (From a talk; ‘Divine Philosophy’)