The second month, or Dawa Nyipa, is paricularly dedicated to the study and meditation of the Guhyasamaja Tantra from the 8th day until the 15th day of the month. Guhyasamaja is referred to as the "supreme and king of all tantras." If one initially understands the Guhyasamaja, then one will automatically understand other tantras. The Guhyasamaja Tantra provides the structure which is the same in al other tantras.
On a larger scale, from the 1st to the 15thgrand ceremonies of Tsongkapa and vajrayana deities are performed in the Ganden Monastery. Each khamsen (each monk belongs to a khamsen, it is like a home fraternity within the larger monastic college)will do different aspects of the ceremonies such as the creation of sand manalas, self-initiations, prayers and so on. The institution of this annual round of ceremonies is considered to be one of the four great deeds of Tsongkapa.
The first fiteen days of the 3rd month or Dawa Sumpa, are devoted to the practices of the Kalachakra, and on the 15thday the ritual is offered. The Kalachakra new year is the the 15thday (full moon) of this month. The Kalachakra Tantra or Wheel of Time is the richest source of Buddhist studies. It encompasses cosmology, astrology, astronomy, subtle energy systems, mind-body relationships and various other related topics embracing the entire universe, leading to Buddhahood.
Dawa Zhipa, or the 4thmonth, is the month called Saga Dawa. The whole month is devoted to prayer and religious observances such as fasting, services for accumulating merit and for purification as well as many other practices. The 15thday is the most important day for Buddhists. More effort should be applied on this day. Retreats can be taken , temples visited, offerings made, and pujas and celebrations such as feasts and picnics.
On this day (the 15thof the month - the full moon of the 4thmonth), Buddha, the universal teacher, entered the womb of his mother, Queen Mayadeva. Thirty-five years later, on the same day he tamed the host of Mara demons and at dusk on the 16th, he attained enlightenment under the Bodhi tree at Bodhgaya. Finally, fifty years later, on the same day, the Buddha passed into parinirvana at Kashinagar.