In one of the beginning episodes he is standing in front of Notre Dame. He makes the point that while its hard to define what a Civilization is he can certainly recognize when he sees it, and that Notre Dame is an excellent example of it .
Whether it turns out this fire of Notre Dame was accidental or Sudden Jihad Syndrome, Europe has foolishly and cravenly opened its doors to the same people that have been struggling to take Europe down for 14 centuries. This fire is now a prime example of the fall of Civilization in Europe . Its a good thing Kenneth Clark did not live to see it, even if he clearly saw the decay of art that is modern art.
I might add the BBC came out with a sequel to this called Civilisations Its very much enamored with the utter decay of art which now is hostile to the progress and rational thought that was the hallmark of Western Civilization. Any surprise the BBC felt the need for that addendum to the original series.
This series can be found on Netflix or Amazon. I saw it last year. It’s at least 30 years old but a brilliant show.