Here is Johansen’s translation, once again, for reference:
‘Since we perceive that we see and hear, it is necessary [b12] that one perceives that one sees either by sight (opsis) or by some other [sense]. But the same [sense] will be [b13] of sight and the underlying colour, so that either there will be two [senses] [b14] of the same thing or it [the sense] will be of itself. And furthermore, if indeed the sense that is of sight were different [b15], then either it will go on to infinity or some sense will be of itself, [b16] so that we should do this in the case of the first [sense]. But there is a puzzle (aporia): for if [b17] perceiving by sight is seeing, and colour or what [b18] has colour is seen, [then] if something is going to see what sees (to horôn), then what first sees [or the first thing that sees] [b19] will also have colour. However, it is clear that perceiving by sight is not one thing; for even [b20] when we are not seeing, we discriminate both darkness and [b21] light by sight, but not in the same way. Moreover, what sees is actually (kai) coloured in a way [b22]: for the sense-organ is in each case receptive of the sense-object without [b23] the matter. That is why perceptions (aisthêseis) and appearances (phantasiai) are present in the sense-organs [b24] even when the sense-objects have departed.’
Here is Johansen’s schema of interpretation for the passage, which he gave on Thursday night. (I quote from the lecture with Johansen’s permission.):
1. Premise: We perceive that we see.
2. Premise: It is either A) by sight that we perceive that we see or B) by another sense.
3. Inference: The same sense will be of both i) sight and ii) colour.
Interpretative note: 3) applies to both options 2) A) and B) above.
4. Inferences: if 2 A), sight will be of itself (by 3 i)); if 2 B), two senses will have the same object (=colour by 3 ii)).
5. Further inferences: if 2 B), either a) there will for each perception that one is perceiving be another sense by which one perceives that perception, in which case there will be an infinite regress of senses, or b) some sense will be of itself.
But not a), so b). If b), best that the sense that is of itself is sight, so 2 A).
But if 2 A), there is an aporia: sight is of colour or what has colour [cf. DA II.7 418a29]; but if so, if what sees (to horôn) is seen, it too must have colour.
6. Aporia defused:
a) There is another way of seeing by sight than seeing colours, for when it is dark we discern by sight that we are not seeing.
b) What sees is in a way colored since the sense-organ receives the sense-object without its matter [i.e. the sense-organ receives the form]. That is why the perceptions and phantasiai can remain in the sense-organs to be perceived later.
It’s a neat and tidy interpretation. One might wonder what could be wrong with it.