Dhanteras falls on the Trayodashi of Krishna Paksha in Kartika and opens the five days of Diwali. It is Dhanvantari Jayanti — the day the physician of the gods rose from the churned ocean holding the pot of amrita. The wealth the day is named for is health first: dhan is what sustains, and the deity who appears is a healer, not a treasurer.

Metal is bought on this day, most often silver or steel, on the understanding that a vessel bought now will not stand empty. The custom is old and the reasoning is plain — a pot is bought before the goddess is invited, two days ahead.

The puja is performed in pradosh kaal. In the evening, thirteen lamps are lit, and one more is set outside the house facing south, for Yama. That single lamp is the one part of Dhanteras that asks for nothing.

Dhanteras marks the day Dhanvantari, physician of the gods and origin of Ayurveda, rose from the churning of the ocean holding the pot of amrit — which is why the day joins health to wealth and a metal vessel is bought to receive that abundance. A second story explains the evening Yama-deep: the young husband of King Hima's line was fated to die by snakebite on the fourth night of marriage; his wife kept him awake with songs and lit lamps and heaped her gold at the door, and Yama, come as a serpent, was so dazzled he left — so a lamp is lit at dusk to turn away untimely death.

Dhanteras opens the five-day Diwali sequence and falls at harvest-end, when there was cash in hand — the reason it became the day for buying gold, silver and new utensils, and for traders to renew their stock and tools. Its link to Dhanvantari has made it modern India's National Ayurveda Day: a turn toward health at the start of the festival, before the light and the feasting.

The 'dhan' of Dhanteras is not coin alone; the day places health first — Dhanvantari before Lakshmi and Kubera — and the Yama-deepa quietly admits mortality even as the wealth is welcomed. It asks that abundance be received with gratitude and a clear eye: what is bought is a vessel, and the true wealth is the wellbeing and length of the lives it serves.

The son of King Hima was foretold to die of a snakebite on the fourth day after his marriage. On that night his young wife let him take no sleep. She heaped her gold and silver ornaments at the door of their chamber, lit lamps everywhere, and told him stories and sang through the whole night.

Yama came in the form of a serpent. The blaze of the lamps on the heaped gold blinded him, and he could not enter. He sat on the pile of ornaments and listened to her singing until the dawn, and then he left without the man. The lamps of Dhanteras are those lamps, and the lamp set facing south is lit for the visitor who was turned away by nothing more than light and a voice that would not stop.