Man’s real nature is Absolute Bliss and Knowledge. He tries to reach this state with the help of his mind and intellect. But the mind constantly gravitates to the sense objects for sensual pleasures from the external world. By such extroverted pursuits man gets involved more and more in the world of objects and accumulates desires which veil the divinity in him.
Man is thus in a helpless condition consumed by numerous desires. The ancient masters knew that he has to turn his attention inwards to gain the state of Absolute Bliss and Knowledge which he foolishly seeks in the external world. With this view of mind, they introduced various rituals and festivals throughout the year to remind man of his supreme goal and ideal. And Dussehra and Vijayadashami are prominent among them.
The great day of Dasara indicates, as the word suggests, Dasa-Papa-Hara or the end of the ten sins. The ten sins are attributed to the ten sense organs through which the mind contacts and gains knowledge of the phenomenal world, and also reacts to the stimuli received from the world of objects. Therefore the idea is that on this sacred day of Vijayadashami or Dasara the ten sins are ended which signifies the end of the mind and therefore the end of the world of plurality when one becomes rooted in the transcendental experience.