आत्मानं रथिनं विद्धि शरीरं रथमेव तु। बुद्धिं तु सारथिं विद्धि मनः प्रग्रहमेव च॥

Know the self as the one who rides, and the body as the chariot. Know the discerning intellect as the charioteer — sārathi — and the mind as the reins held in its hands.

Katha Upanishad 1.3.3

SARATHI A wearable voice companion, carried on foot through Black Rock City. It listens, it answers out loud, and it runs entirely on the battery in the pack. Nothing it hears leaves the device.

If you met it out there

SARATHI is worn, not held. Ask it where something is and it will work out the walk from where you are standing and tell you which way to turn. Ask it something harder and it will answer from the Upanishads and the Gita, in the voice of a charioteer who has had this conversation before.

It is slow on purpose. It thinks for a few seconds before it speaks, the way you would want a charioteer to.

It is also, plainly, a joke at the expense of the smart glasses that record you. This one has no camera, keeps no transcript, and forgets you the moment you walk away.

How it works

Everything runs on the wearer's body. There is no server, no account, and no connection to anything — which is the only architecture that survives a week with no signal.

Computer

NVIDIA Jetson Orin Nano, battery powered, worn in a pack

Hearing

Four-microphone array with echo cancellation; speech transcribed on-device

Thinking

A small quantized language model running locally, with retrieval over a text corpus stored on the device

Voice

Local speech synthesis, streamed sentence by sentence so it starts speaking before it has finished thinking

Position

A USB GNSS receiver, read locally only

Network

None

What it has read

The philosophical corpus is the Katha Upanishad, the Bhagavad Gita, and a set of notes on the classical schools of Indian thought.

The navigational corpus is built from Burning Man Project's published open data: the 2026 city plan and street grid, surveyed plaza and portal coordinates, public toilet locations, and the public theme camp placements. Directions are computed geometrically from the polar street grid rather than guessed at by the language model, so a walking instruction is arithmetic, not invention.

Placement data is a snapshot and camps move. SARATHI says so when it answers, and points people to Placement HQ for ground truth.

What it collects

Nothing. There are no accounts, no logging, no analytics, and no uplink. Audio is transcribed in memory and discarded. Location is read from the receiver, used to compute the current walk, and never written down or transmitted. When the battery dies, the day is gone.

What it costs

Nothing, to anyone, ever. SARATHI is a gift. It is not a product, it is not for sale, it carries no advertising, and it is not a demonstration of anything anybody sells. Speak to it and it answers; that is the whole transaction.