Medha means purification (ceremony); ashwa means today, now; that which was not yesterday, not tomorrow, but today. Dasharatha means one who can run ten chariots at a time. Kaushalya means one who is very skillful. So, when Dasharatha and Kaushalya came together, and did the Ashwamedha yagya, which means purifying the present moment, that is when Rama was born. This is the spiritual significance of Sri Rama’s birth.