The Wheel of the Year

At Yule, which occurs at the time of the Winter Solstice in December, the Lady gives birth to the Lord and rests from Her labour.
At Imbolc, in February, the Lord is seen as a small boy, and the Lady recovers from giving birth.
Ostara marks the first day of Spring and the awakening of the Earth. At this time, the Lord is seen as a growing youth.
At Beltaine, the Lord has grown to manhood. He falls in love with the Lady, and They unite, producing the bounty of Nature. The Lady becomes pregnant by the Lord.
The Summer Solstice is the point in Midsummer when everything in Nature is at its peak, growing and lush. The Lord and Lady are both at the height of Their powers.
Lughnassadh is the day in August of the first harvest. The first grains are cut, and the Lord begins to weaken.
At Mabon, the second harvest, the Lord is coming to His end. The days grow shorter, and Earth readies for the slumber of Winter.
At Samhain, in October, the Lord dies only to be reborn of the Lady again at Yule.