Developing the preliminary sign (parikamma nimitta)

Gaze at the kasina until you can see it clearly with eyes open and hold its image for a few seconds with eyes closed.

Why it works

Sustained gaze builds a strong retinal and cortical representation of the object. When the eyes close, this representation persists briefly as an after-image, then as a short-term visual memory trace. Repeating the open-close cycle conditions the mind to hold the image with increasing clarity and duration — this is the first stabilisation of attention on a single object.

How to do it

1. Gaze at the kasina disk steadily for thirty to sixty seconds without letting attention drift.
2. Close the eyes and hold the image exactly as it appeared — same size, same position.
3. When the image fades, open the eyes and reacquire the disk; repeat the cycle.
4. The session goal is simply to make the transitions smoother — not to strain for a longer hold.

Evidence

The after-image and short-term visual memory mechanism is well established in cognitive neuroscience. Using it deliberately as a practice anchor is classical Theravada instruction rather than a tested protocol. (mechanistic)

Modern neuroscience supports the mechanism but the specific protocol derives from the Visuddhimagga.

Common mistake

Forcing the after-image to stay by squinting or intense effort — relaxed attention holds the image longer than strained attention.