²²My logic is that if something pleasant is not present as in 1b, the point is that one actually wants that pleasant thing to be present, so this is also a question of not getting what one wants, as in 1a. The same logic shows that 2a and 2b are really the same thing. The points 1b and 2b present the difficulty that they use the terms pleasant (or “pleasing” in the translation quoted above) and unpleasant (or “displeasing”), much like the IASP definition of pain. (Alternative translations of these two words include “beloved”/”unbeloved” (Thanissaro Bhikkhu) “loved”/”loathed” (Nanamoli), “liked”/”disliked” (P. Harvey), and indeed “pleasant”/”unpleasant” (Piyadassi Thera), given at https://www.accesstoinsight.org/tipitaka/sn/index.html#sn56.) I suggest the key here is that “pleasant” is here assumed to necessarily lead to wanting (and “unpleasant” to aversion), and thus the Buddha is really talking about desire or wanting and aversion. When he specifically mentions wanting at the end of the quote, that may be seen as a kind of summary of the two first sentences.