special. In the Upanishads, states Diana L. Eck, the "crossing over" refers to the "spiritual transition and transformation from this world to the world of Brahman, the Supreme, the world illumined by the light of knowledge". The emphasis in the Upanishads, in Tirtha context is on spiritual knowledge, instead of rituals, and this theme appears in the Hindu epics as well. Holy sites The Dharmasastras and the Puranas, states Kane, assert numerous descriptors for what is holy, including all mountains, all of Himalayas, all rivers, lakes, dwellings of Rishis (sages), temples, cowpens, great forests, and all seas. This tradition traces back to the Rigveda, where Aranyani (large forest) is referred to as a deity. The reverence for rivers and water bodies is traceable to the Nadi Stuti, or the river-hymn, in hymn 10.75 of the Rigveda. Pilgrimage sites are not prominent in Dharmasastras such as Manusmriti and Yajnavalkya Smriti, but they are found in the epic Mahabharata and the Puranas.< Most Puranas include large sections on Tirtha Mahatmya along with tourist guides, which describe sacred sites and places to visit, particularly the Padma Purana, Skanda Purana, Vayu Purana, Kurma Purana, Bhagavata Purana, Narada Purana, Devi Bhagavata Purana, Vamana Purana, Linga Purana, Brahma Purana, Brahmanda Purana and Bhavishya Purana. In ancient texts, Varanasi (Benares, Kashi), Rameshwaram, Kanchipuram, Dwarka, Puri, and Haridwar have been mentioned as particularly holy sites, along with geographies where major rivers meet (sangam) or join the sea. The Kumbhamela, which rotates at a gap of three years, between Prayaga (renamed to Allahabad in the late medieval era), Haridwar, Ujjain and Nasik, remain popular into the modern times, with tens of millions of Hindus participating. Reasons Some pilgrimage are part of a Vrata (vow), which a Hindu may make for a number of reasons. It may mark a special occasion, such as the birth of a baby, or as part of a rite of passage such as a baby's first haircut, or after healing from a sickness. It may, states Eck, also be the result of prayers answered, or consequent to a vow a person had made if his or her prayer were to come true, such as the well being of a family member, or overcoming poverty or destitution or a challenging situation. An alternate reason for Tirtha, for some Hindus, is to respect wishes or in memory of a beloved person after his or her death. This