Parasya saktir vividhaiva sruyate (Svetasvatara Upanisad 6.8). In the Vedas it is said that the potencies of the Supreme Personality of Godhead are called by different names, such as yogamaya and mahamaya. Ultimately, however, the Lords potency is one, exactly as electric potency is one although it can act both to cool and to heat. The Lords potency acts in both the spiritual and material worlds. In the spiritual world the Lords potency works as yogamaya, and in the material world the same potency works as mahamaya, exactly as electricity works in both a heater and a cooler. In the material world, this potency, working as mahamaya, acts upon the conditioned souls to deprive them more and more of devotional service. It is said, yaya sammohito jiva atmanam tri-gunatmakam. In the material world the conditioned soul thinks of himself as a product of tri-guna, the three modes of material nature. This is the bodily conception of life. Because of associating with the three gunas of the material potency, everyone identifies himself with his body. Someone is thinking he is a brahmana, someone a ksatriya, and someone a vaisya or sudra. Actually, however, one is neither a brahmana, a ksatriya, a vaisya nor a sudra; one is part and parcel of the Supreme Lord (mamaivamsah), but because of being covered by the material energy, mahamaya, one identifies himself in these different ways. When the conditioned soul becomes liberated, however, he thinks himself an eternal servant of Krsna. Jivera svarupa hayakrsnera nitya-dasa. [Cc. Madhya 20.108]. When he comes to that position, the same potency, acting as yogamaya, increasingly helps him become purified and devote his energy to the service of the Lord.