It would seem that human beings are not able to describe, nor perhaps to imagine, happiness except in terms of contrast. ...
I wonder if this also works in reverse: humans are incapable of describing or imagining unhappiness except in terms of contrast.
This reminds me of a line that goes something like: revolutions happen not because of poverty but through the process of a society becoming poorer.
I don't think it's the case that most of them start because the society as a whole had become poorer, but because some particular segment has, while others accumulate wealth. It's not really worth having a revolution if there's nothing of value to seize. A lot of revolutions started as tax revolts by the wealthy, in fact -- the french revolution and english civil war come to mind. It was only after central authority collapsed that events outpaced the initial instigators.
‘No taxation without representation!’
Which is probably why successful oppressive regimes (the ones that don't look as such) boil their frogs very slowly.