01What Dhanteras is
Dhanteras, or Dhanatrayodashi, is the thirteenth day of the dark half of Kartika (Ashwin in the south's reckoning), two days before Diwali and the first of its five days. Dhan is wealth and teras the thirteenth. The day honours Lakshmi and Kubera, the keeper of the gods' treasury, and Dhanvantari, the physician of the gods, whose birthday it is held to be; Ayurveda marks it as Dhanvantari Jayanti.
02The story told of it
The Puranas tell of the churning of the ocean of milk by the gods and the asuras. Among the treasures that rose from it, Lakshmi came seated on a lotus, and on the thirteenth day Dhanvantari rose holding the pot of amrit, the nectar the gods had churned for. Because both wealth and the healer's art came out of the ocean in those days, the tradition joins them on Dhanteras, and the pot Dhanvantari carried is why a new vessel is bought on this day.
03How it is kept
Houses are cleaned and the door marked with rangoli and the small footprints of Lakshmi walking in. The tradition holds the day good for buying metal, so families buy gold, silver or a new brass or steel vessel, and bring it home before the evening puja. The puja is made in Pradosh, after sunset, to Lakshmi, Kubera and Ganesha, with a lamp of ghee, flowers, sweets and coriander seeds. After dark a lamp of flour or clay, Yama Deepam, is lit at the door facing south.
04How the day is chosen
Dhanteras is kept on the day Krishna Trayodashi is current in Pradosh, from sunset through the first fifth of the night, because the puja belongs to the evening. The muhurat is the part of Pradosh when Vrishabha, a fixed lagna, is rising, which the tradition prefers so that what is begun stays. Yama Deepam is lit on the evening Trayodashi is current at sunset.
05Dhanteras in other years