Dhana Trayodashi (or Dhanteras) is the first day of Diwali, Festival Lights.  Dhanvantari is worshipped on occasion of Dhanvantari Trayodashi. Dhanvantari is considered to be the teacher of all physicians and originator of Ayurveda.  On day of Dhantrayodashi Goddess Lakshmi came out from ocean milk during churning of Sea. Hence, Goddess Lakshmi, along with Lord Kuber is worshiped on Trayodashi.  On Dhanteras World consider it auspicious to purchase gold or silver or at least one item of choice.  It is believed that new "Dhan" or some form of precious item or a book is a sign of good luck. "Lakshmi Puja" is performed in evenings when tiny Diyas of clay are lit to drive away shadows of evil spirits.  Devotional Verses in praise of Goddess Lakshmi, are also sung. Wealth increasing Times Sutras, blessings of Goddess Wealth.     Author, Awarded Nobel.