Yeah it's a shame, but I don't see how it means "a loss of grammar", pace Barzun.

Barzun may have a tendency to let some facts run away with him. F.i. he writes that Leonardo da Vinci had no use for and even hated music. I have found no evidence of that. Others say he was a great musician. No evidence of that either. There is one tiny line of notes by his hand. Not very impressive. It's more likely that he liked or loved music and even played a lute or so, but could not add "musician" and "composer" to his homo universalis record.

(still I enjoy the read)