Ostara is a modern Neopagan holiday. It is loosely based on several holidays which were celebrated around the spring equinox (when day and night are nearly of equal length). The modern holiday does not have a strong relation to any known historical Pagan religious observation. A historically correct reconstruction is impossible.
The name Ostara goes back to Jacob Grimm, who, in his Deutsche Mythologie, speculated about an ancient German goddess Ostara, after whom the Easter festival (German: Ostern) could have been named. Grimm's main source is De temporum ratione by the Venerable Bede. Bede had put forward the thesis that the Anglo-Saxon name for the month of April, Eostur-monath, was named after a goddess Eostre.
Ostara is one of the four lesser Wiccan holidays or sabbats of the Wheel of the Year. Ostara is celebrated on the spring equinox, in the Northern hemisphere around March 21 and in the Southern hemisphere around September 23, depending upon the specific timing of the equinox. Among the Wiccan sabbats, it is preceded by Imbolc and followed by Beltane.
In the book Eight Sabbats for Witches by Janet and Stewart Farrar, the festival Ostara is characterized by the rejoining of the Mother Goddess and her lover-consort-son, who spent the winter months in death. Other variations include the young God regaining strength in his youth after being born at Yule, and the Goddess returning to her Maiden aspect.
Ostara is the virgin Goddess of spring. This holiday concerns the deity's trip to the underworld, and their struggle to return from the Land of the Dead to Earth. When they accomplish this return, they have a life renewed. It was considered bad luck to wear anything new before Ostara, so the people would work through the winter in secret to make elegant clothes for the Sabbat celebration. The entire community would gather for games, feasting, and religious rituals while showing off their clothing.
The lamb was another symbol of Ostara, and was sacred to the Virgin Goddess of Europe, the Middle East, and North Africa.
The modern belief that eggs are delivered by a rabbit known as the Easter Bunny comes from the legend of the Goddess Eostre. So much did a lowly rabbit want to please the Goddess that he laid the sacred eggs in her honor, gaily decorated them, and humbly presented them to her. So pleased was she that she wished all humankind to share in her joy. In honor of her wishes, the rabbit went through the entire world and distributed these little decorated gifts of life.
^ Grimm, Jacob (1835). Deutsche Mythologie (German Mythology); From English released version Grimm's Teutonic Mythology (1888); Available online by Northvegr © 2004-2007, Chapter 13, page 10+
Life and Peace be with You --Cinosam