Continuo Practice Lost by Mendelssohn's Era

Bach's larger vocal works were neglected until Mendelssohn partly because the improvisatory continuo practice essential to the passions had become completely extinct by Mendelssohn's time; Mendelssohn had to harmonize the continuo part and add brass and wind to fulfill it, and he treated the passion mainly as storytelling, cutting most arias, making his revival fundamentally different from modern historically-informed performance.