The Celtic Festival of Beltaine which marks the beginning of summer in the ancient Celtic calendar is a Cross Quarter Day, half way between the Spring Equinox and the Summer Solstice. While the Beltaine Festival is now associated with May 1st, the actual astronomical date is a number of days later. The festival was marked with the lighting of bonfires and the movement of animals to summer pastures.
In Irish mythology, the beginning of the summer season started with the Fire Festival at Beltaine. Great bonfires would mark a time of purification and transition, heralding in the season in the hope of a good harvest later in the year, and were accompanied with rituals to protect the people from any harm by otherworldly spirits.
In my novel, The Keepers of Éire, the Tuatha dragon clan members renew their sworn oath to protect the land and its inhabitants, and rejuvenate the dragons’ magic by reciting the clan motto: Ni neart go cur le cheile (There is no strength without unity) and flying over the ley lines at the Beltaine Fire Festival on the Hill of Tara. Also, my two protagonists, Christian and Devan, officially pair up with their dragons (Roarke and Dochas, respectively) in a Chosen Ceremony, and end with both humans in great peril. To find out how the story ends, check out The Keepers of Éire.
May you enjoy Beltaine with this image from http://www.irelandcalling.ie