Man entertains numerous desires. He can successfully fulfil only a few of them by his own efforts through normal means. As long as the unfulfilled desires fill his heart he cannot have peace. Here comes the role of the śruti or the Vedas which prescribe certain specific rituals to obtain specific objects of desire by divine grace. These are the alaukika-upāyas or supernatural means, by resorting to which he can satisfy his desires legitimately.
These include the Śyena-yāga or means for the destruction of the enemy. But the use of these methods is forbidden by the śruti itself and one has to be guided by its instructions. In this respect śruti is said to be like a light illuminating equally the path to be chosen and the thorn to be avoided. The choice is left to the person for whom guidance to choose properly has also been provided.