Number 85 - To see a tree asmiling.

Modern ears are used to an overall sleekness of sound when listening to Mozart and Haydn, because today's violins have louder strings played with longer bows. The horns have valves. All the instruments project more in a concert hall.

The instruments of the 18th century don't blend as seamlessly with each other and, when led by someone like Weil, who likes to highlight orchestral textures in unsubtle ways, the air vibrates with all kinds of rhythms and timbres usually absent from a modern symphony.

The effect in an intimate space like Trinity-St. Paul's grabs one's attention, especially with such well-worn fare as Mozart's Eine Kleine Nachtmusic, from 1787, and Haydn's C-Major Symphony No. 97, one of the works he wrote for his London visit in 1792.

Weil made both pieces sound fresh. They danced enticingly, showing off their composers' keen sense of musical invention.

For Mozart's 1785 Concerto No. 20, in the dramatic key of D minor, Brautigam played his solos on a reproduction fortepiano " a delicate instrument that fills the evolutionary gap between a harpsichord and the pianoforte.

This was the only time I missed the wider dynamics and much, much stronger musical presence of a piano. The fortepiano seemed lost amidst the 32-member orchestra, sounding as if located in an adjoining room. Brautigam played nicely. He performed his own cadenzas " something Mozart would have improvised at the concerto's premiere " but even they seemed unduly modest.

Hearing music on original instruments is an ear-opening experience. But it's not always the most satisfying one in the 21st century.