I’ve come very to this late, but I want to comment on and reinforce a trend in the thread, which is that we understand rūpa as reflecting sensory experience rather than substance. I’m in the middle of trying to articulate this so what I’m writing here is entirely provision and subject to revision.
I don’t think rūpa was ever intended to convey ideas like “body” and “matter”, that said, it is an historical fact that Buddhists ourselves have attributed this meaning to the word. Indeed I routinely see academics translating rūpa as “matter” (e.g. Prof. Jonathan Silk). Still, we can in fact understand rūpa entirely in epistemic/phenomenological terms without doing any violence to Buddhavacana.
When we look at rūpa amongst the āyatana/dhātu schema we see this relation:
rūpa is to the eye as sound is to the ear.
That is to say, just as sound emanates from an object, crosses the space between us, hits the ear, and causes an aural sensation; so also with rūpa and the eye.
If rūpa meant “substance”, “body”, or “matter”, then seeing would be caused by matter entering the eye. Ouch. In modern terms, entirely anachronistic in a Pāli context but nonetheless our own framework, rūpa must simply be “reflected light”. In this context, I think “form” tends to make English-speakers think in terms of substance which is misleading. To avoid this misinterpretation, I translate rūpa as “appearance”.
There really is no discussion of objects or the nature of objects in Pāḷi. What we see is more like discussion of sensory experience in terms of the arising and ceasing of sensory experiences, with a view to ending them all (nibbāṇa). Although all Buddhists trade in metaphysics, in these discourses the topic is experience rather than reality. An objective reality is entirely consistent with Buddhist doctrines, but Buddhists themselves didn’t have anything much to say about it because they were obsessed with the cessation of sensory experience in meditation and the subsequent state of absence of sensory experience.
Moreover, we can extend this usage. As some of the previous posters argued, we can see rūpakkhandha as a generalisation of rūpa qua visual appearance, to a general sense of “sensory appearance”. In other words, rūpa stands as a metonym for the arising of sensory experience across the sensory modes. With this shift in emphasis, all of the khanhas now refer directly to aspects of sensory experience, which makes the set more coherent. Having appeared in our sensorium the sensory experience creates a valence of positive or negative affect (vedanā); we recognise and name the experience we are having (saññā), we have an occasion to commit kamma (saṇkhārā), and then we discriminate the object we are experiencing (viññāṇa).
So we can talk about khandhas from an entirely epistemic point of view without invoking substance or matter. Note also that from discrimination of the object, comes papañca.
Again, we can extend this reading to nāmarūpa and in doing so we see why the Mahānidāna Sutta begins with viññāna and nāmarūpa conditioning each other.
If rūpa is appearance, then in the context of nāmarūpa, rūpa can be seen as the basis on which one attaches a label (nāma). For a person, their rūpa is how the look (facial features, habitual expressions, haircut, etc), how they sound, and so on. Rūpa is again “appearance” in a general sense. The appearance depends on an object and that gives it a set of distinctive qualities that are recognisable.
If viññāna-skandha is the discrimination (or identification) of the object behind the sensory experience, then we can see that this might entail first recognising the attributes of it, and then giving it a name. Or in other words viññāna consists of recognising an object from its characteristics: nāma on the basis of rūpa. In this view, viññāna and nāmarūpa amount to different ways of looking at the same process. And from this emerges papañca.
So rūpa means “appearance”: more specifically “visual appearance”, but figuratively speaking any kind of “sensory appearance”.
Now. It may or may not be the case that anyone in the ancient world thought this way. I think this way and it appeals to me for several reasons. Firstly, I have one (flexible) definition of rūpa and it serves all the functions I need it to: the basic definition “appearance” doesn’t radically change with the context. Secondly, I can discuss the idea entirely in epistemic or phenomenological terms without invoking metaphysics (i.e. existence, reality, truth and their negations). Thirdly it unexpectedly helps to make sense of an odd bits and pieces like the weird nidānas in the Mahānidāna Sutta: not an inconsequential text. Lastly it is broadly consistent with my attempts to read all Buddhist texts as concerned with the arising and, especially, the ceasing of sensory experience (following on from Sue Hamilton’s epistemic account of the khandhas).
The avoidance of metaphysical commitments based on the texts in which this concept is described is important because it side-steps interminable discussions about the existence or non-existence of this or that. Do dharmas exist? The question is ayukta (unconnected, irrelevant). Do dharmas not exist? Ayukta. Any discussion of the metaphysics of dhammas or self or whatever misses the point. The point is that we can, through concerted and systematic efforts, make all dhammas cease and then dwell in a state in which no dhammas arise aka suññatāvihāra.
I suspect that everyone in Indian knew this, but they all came to different conclusions about it. For Brahmins the state of emptiness was interpreted as brāhmana (or Brahmā); for Saṃkhyā it was puruṣa manifesting when prakṛti became quiescent. And for Buddhists it was nibbāna: suññatā is like death - we have a text to help us tell the difference between one in that state and a dead man, i.e. MN 43 (PTS MN I 296).
Incidentally, this way of thinking has been mainly inspired by studying the Heart Sutra (in which rūpa plays a prominent role). And one of the really neat things about this is that the same explanation for rūpa in early Buddhist texts works equally well in the Prajñāpāramitā context. I’m coming around to thinking of Prajñāpāramitā as an ancient (largely oral: guru to śiṣya) lineage within Buddhism that found a new literary voice under the Kushan kings in Gandhāra; not as a new or breakaway lineage. Once we repair the persistent errors in the Heart Sutra, it is very much consistent with the Pāḷi discourses on cessation of sensory experience in samādhi.
As a technical term:
rūpa is to the eye as sound is to the ear (and tangibles are to the body).
rūpa is “appearance”; in the narrow sense of the appearance of a visual sensory experience.
rūpa can also stand as metonym for all the senses in general (sight often stands in this relation to the other senses).
- The rūpa of an object is how we recognise or discriminate (viññāna) the object and thus give is a name (nāma).
This does not obviate the conventional, non-technical use of rūpa in Pāḷi. It’s an attempt to make sense of doctrine, not language more generally.