Pergolesi's incomparable setting of the Stabat Mater rose to great fame immediately following the composer's untimely death at the age of 26. Known for its beautiful arias and duets for soprano and alto, the writer and composer Jean-Jacques Rousseau praised the opening movement as "the most perfect and touching duet to come from the pen of any composer." The uniquely captivating music of Pergolesi's setting attracted Johann Sebastian Bach about a decade later, inspiring him to compose an arrangement of the instrumental parts that included a very elaborate part for the violas. After all, Bach was a fine violist himself, and he must have yearned for the opportunity to contribute to Pergolesi's beautiful music in a way that would flatter its composer.
The start of the 18th century was one of the great epochs of superb virtuoso violinists. Pietro Locatelli was one of those, and his greatest contribution to Baroque music is a collection of violin concertos along with Capricci ad libitum (cadenzas), published in 1733. The last concerto of the set has the well-earned nickname “Il labirinto armonico – Facils aditus, difficilis exitus” (“The harmonic labyrinth – Easy access, difficult exit”). Both of its cadenzas are intricate, complex, and lengthy, including extended journeys through a multitude of keys, living up to the meaning of “labyrinth,” often sounding like a maze of showy fireworks. But the effect is astounding and not at all frivolous. In fact, the almost daredevil physicality of Locatelli’s written-out cadenzas led eventually to the next era of phenomenal violin virtuosity in the hands of Niccolò Paganini, nearly a century later.