How many people are celebrating the fact that, last week, one of Europe’s most inspired writers about music, modern art and aesthetics celebrated his 90th birthday? The answer is relatively few, which might seem surprising. He is a world-renowned authority on the grotesque and the absurd — territory through which he darts mischievously in his poems, originally composed in his native German. But you have to turn to his essays written in English to experience his refined sarcasm, which is either delicious or mortifying, depending on whether you feel incriminated by his strictures against intellectual laziness. He is quirky and rigorous — a combination associated with his beloved Dada, a movement I’d written off as an embarrassment until I read his dazzling essay on the subject in the New York Review of Books.