By the time Mozart turned twenty he was already one of the most skilled composers of his day. His output included not only symphonies and concertos but piano pieces, serenades, arias, operas and smaller species of musical theater, songs and church music. Symphony No. 40 in G Minor forms the centerpiece of the "final trilogy." It is a work of complex character, one whose music embodies passion and formal elegance, sorrow and exultation, darkness and light. Mozart's brilliant use of counterpoint, the simultaneous sounding of different melodic strands, makes the finale of his "Jupiter" Symphony one of the outstanding musical achievements of the Classical period.