Imagine being Picasso and walking out of the Lascaux Cave and muttering, “We have learned nothing.” Imagine this neither being facetious nor a judgment of utter disappointment.
Imagine it just being a statement of fact. Imagine it being just a pronouncement of what is, an objective enough comment. Not only has art not moved in 17,000 thousand years, but from that time on we as humans beings ourselves have not learned a thing.
As a statement of fact, it is quite a thing for one man to say, for him to have said. As a joke of sorts, it is the typical sort of flyaway comment made all the time. That, like so many things said sarcastically or in jest, is pretty easy to take.
But I rather think, like the setting of the sun done for the day, that it was made in the spirit of simple truth rather than the wry, self-serving smile of irony.