Lord Krishna's Janmashtami and his wisdom " Yadaa yadaa hi dharmasya"

Janmashtami celebrates the birth of Lord Krishna, when the Moon entered the house of Vrishabha at the constellation of the star Rohini, on the 8th day of the second fortnight of the month of Sravana, which corresponds to the month of Bhadrapada Krishnapaksha at midnight according to the Barhaspatyamana, in the year of Visvavasu, 5,172 years ago in Mathura. 

The eighth Avatara, whenever Dharma declines and evil predominates, to establish Dharma and vanquish evil. In the Gita (4/78) the Lord has ordained: 

"Yadaa yadaa hi dharmasya glanir bhavati Bharat; 
Dharma sansthaapanaarthaaya sambhaavami yuge yuge." 

Lord Krishna that perhaps is the omniscient charioteer delivers the wisdom of the Bhagavad Gita to Arjun before the great war of Mahabharata – a Hindu epic. Therefore Krishna is also known as Parthasarathi, or Arjun's/Partha's charioteer. 

Sri Krishna who manifests all levels of joy, is also the source of spiritual joy, which overrides mental or emotional joy, just as emotional joy overrides physical joy. If all the three are integrated and interdependent, then the observance of the festival takes on the full meaning of Krishnaarpanamastu - let everything be offered to Sri Krishna. 

Janamashtami is celebrated with great fervour all over India especially at Mathura and Brindavan where Lord Krishna spent his childhood. Temples and homes are beautifully decorated and lit. On Janamashtmi, devotees keep daylong fasts and keep themselves awake while chanting holy songs, until midnight follows.