I originally posted this in the Feedback section in the possible errors and typos thread but didn’t receive a response. I thought I might have better luck here, in case those knowledgeable in Pāli or, even better, Ven. @sujato might reply.
In DN 9, the sentence “ Tassa yā purimā rūpasaññā, sā nirujjhati ” is translated as “The perception of luminous form that they had previously ceases.”
If this isn’t a typo, I’m curious as to how the adjective “luminous” comes into this translation.
The word rūpa fundamentally means "that which appears (to the eye or the mind). In the case of jhana and similar meditation contexts, rūpa is commonly used in the sense of a “vision” or light that appears in the mind during meditation. This is what in modern times is called a nimitta. Most translators do not represent this different usage, with the result that, I believe, such passages become difficult to understand. So I add “luminous” to try to bring out the idea that such things are if you like “apparitions” or shapes that are seen by the inner glow of the mind.
And what is the way of developing immersion further that leads to gaining knowledge and vision?Katamā ca, bhikkhave, samādhibhāvanā bhāvitā bahulīkatā ñāṇadassanappaṭilābhāya saṃvattati?
It’s when a mendicant focuses on the perception of light, concentrating on the perception of day,
Idha, bhikkhave, bhikkhu ālokasaññaṃ manasi karoti, divāsaññaṃ adhiṭṭhāti—
regardless of whether it’s night or day.
yathā divā tathā rattiṃ, yathā rattiṃ tathā divā.
And so, with an open and unenveloped heart, they develop a mind that’s full of radiance.
Iti vivaṭena cetasā apariyonaddhena sappabhāsaṃ cittaṃ bhāveti.
This is the way of developing immersion further that leads to gaining knowledge and vision.
Ayaṃ, bhikkhave, samādhibhāvanā bhāvitā bahulīkatā ñāṇadassanappaṭilābhāya saṃvattati.
Samādhibhāvanā Sutta AN 4.41
This perception of light might develop a luminous image. However, when a person meditates using one of the kasinas that concentrates on patavi apo or vayo obtaining a luminous image is kind of doubtful. There may be for tejo (fire element).
The perception of luminous form that they had previously ) ceases.
Tassa yā purimā rūpasaññā, sā nirujjhati.
At that time they have a subtle and true perception of the dimension of infinite space.
Ākāsānañcāyatanasukhumasaccasaññā tasmiṃ samaye hoti, ākāsānañcāyatanasukhumasaccasaññīyeva tasmiṃ samaye hoti (DN9).
DN 9 discusses about eight jhānas where it is about general characteristics of jhānas. Therefore, the translation should also be general.
This shows in first four jhanas meditator clearly perceives the form realm, with his senses, while in formless (arūpa) jhanas such perception ceases.
Hope sense of vision means nimitta (image).
Image is not always visibile/ visual.
When it comes to mindfulness of breathing the imgae is tactile not visual. Visuddhimagga also mention the possibility of a tactile image but it also says there may be some visual images.
Thus in breathing in and out, air touches the nose or the lip and causes the setting-up of air perception mindfulness. This does not depend on colour or form.This is called the image (Nimitta). If the yogin develops the image (Nimitta) and increases it at the nose-tip, between the eye-brows, on the forehead or establishes it in several places,he feels as if his head were rilled with air. Through increasing in this way his whole body is charged with bliss (sukha). This is called perfection (Vimuttimagga).
Obviously there are no detailed explainations about meditation experiences in EBTs. Therefore, these explainations comes from later sources and personal experiences.