Vishwakarma Puja falls on Kanya Sankranti, the day the Sun leaves Simha and enters sidereal Kanya (Virgo) — the last day of the month of Bhadra in the Bengali and Odia reckoning. Because it is fixed by the Sun and not by a tithi, it does not wander through the calendar the way lunar festivals do: it falls on 17 September in most years and on 16 September in some, and never outside that pair in the years this page covers.

What is worshipped on this day is work itself. Lord Vishwakarma is the divine craftsman, the deity of mechanical sciences, architecture and Vastu Shastra, and on his day artisans, engineers, drivers, weavers, mechanics, carpenters, smiths and factory workers set down their tools, clean them, garland them and worship them rather than use them. A lathe, a loom, a truck, a sewing machine and a laptop are all treated the same way: as the instrument through which a living is made, and therefore as something that deserves gratitude.

It is one of the few Hindu festivals observed at the workplace rather than the home, which is why it reads as an industrial holiday across eastern India while remaining, in substance, a thanksgiving for skill.

Vishwakarma Puja is old as a devotion and young as a factory holiday. The Rigveda already praises Vishvakarman as the all-maker who shapes heaven and earth, and the Puranas name him the architect of Dwarka, of Indraprastha and of the golden Lanka. The workshop festival that India keeps today, however, grew with industry: as foundries, railway sheds, printing presses, garages and mills spread through Bengal, Bihar, Jharkhand, Odisha, Assam and eastern Uttar Pradesh, the craftsman's household rite moved onto the shop floor, and the day became the one holiday of the industrial calendar that belongs to the tools themselves.

The Rigveda's Vishvakarma Sukta (10.81 and 10.82) addresses him as the one "whose eyes are on every side, whose face is on every side, whose arms and feet are on every side", the maker who welds together heaven and earth. The Mahabharata and the Puranas extend this into craft: he fashions the Sudarshana Chakra of Vishnu, Shiva's Trishula and the spear of Kartikeya. The Vishvakarma Prakasha and the Shilpa Shastras carry his name as the authority behind architecture, sculpture and Vastu.

When the gods needed a world to live in, it was Vishwakarma who drew it. To help Brahma in the act of creation he set out the blueprint of the earth, and afterwards he built for the gods whatever the stories required: Swargaloka itself, the city of Dwarka for Krishna, the hall of Indraprastha for the Pandavas, Sudamapuri for Sudama, and the golden Lanka — which, the tale goes, he raised for Shiva and Parvati only for Ravana to ask for it as the priest's fee and carry it away.

He made the instruments of the gods as well as their houses. From the dust of the Sun, ground down on his wheel so that the world could bear its light, he fashioned the Sudarshana Chakra of Vishnu, the Trishula of Shiva and the spear of Kartikeya. The lesson the craftsmen take from this is plain enough: the tool is not lesser than the hand, and the one who makes well is close to the one who made everything.