Renan dismissed de Sacy as orthodox and lacking critical insight

Evidence

Renan judged him to be ‘the typical orthodox scholar… but if one looks further, one sees the strange spectacle of a man, who, though he possesses one of the vastest eruditions of modern times, has never had an important critical insight’. More generally he had a disparaging opinion of earlier French Orientalists, especially by comparison with the learned Germans: ‘quelles misères et songez à ce qui se passait alors en Allemagne’. — Robert Irwin, For Lust of Knowing, 294