According to Monier Williams and Yudit Greenberg, linga literally means 'mark, sign or emblem', and also refers to a "mark or sign from which the existence of something else can be reliably inferred". It implies the regenerative divine energy innate in nature, symbolized by Shiva. Some scholars, such as Wendy Doniger, view linga as merely a phallic symbol, although this interpretation is criticized by others, including Swami Vivekananda, Sivananda Saraswati, Stella Kramrisch, Swami Agehananda Bharati, S. N. Balagangadhara, and others. According to Moriz Winternitz, the linga in the Shiva tradition is "only a symbol of the productive and creative principle of nature as embodied in Shiva", and it has no historical trace in any obscene phallic cult. According to Sivananda Saraswati, westerners who are curiously passionate and have impure understanding or intelligence, incorrectly assume Siva Linga as a phallus or sex organ. Later on, Sivananda Saraswati mentions that, this is not only a serious mistake, but also a grave blunder. The worship of the lingam originated from the famous hymn in the Atharva-Veda Samhitâ sung in praise of the Yupa-Stambha, the sacrificial post. In that hymn, a description is found of the beginningless and endless Stambha or Skambha, and it is shown that the said Skambha is put in place of the eternal Brahman. Just as the Yajna (sacrificial) fire, its smoke, ashes, and flames, the Soma plant, and the ox that used to carry on its back the wood for the Vedic sacrifice gave place to the conceptions of the brightness of Shiva's body, his tawny matted hair, his blue throat, and the riding on the bull of the Shiva, the Yupa-Skambha gave place in time to the Shiva-Linga. In the text Linga Purana, the same hymn is expanded in the shape of stories, meant to establish the glory of the great Stambha and the superiority of Shiva as Mahadeva. The oldest known archaeological linga as an icon of Shiva is the Gudimallam lingam from 3rd-century BCE. In Shaivism pilgrimage tradition, twelve major temples of Shiva are called Jyotirlinga, which means "linga of light", and these are located across India. Avatars Puranic scriptures contain occasional references to "ansh" – literally 'portion, or avatars of Shiva', but the idea of Shiva avatars is not universally accepted in Shaivism. The Linga Purana mentions twenty-eight forms of Shiva which are sometimes seen as avatars, however such mention is unusual and the avatars