In the 19th century it was standard[REF] to have the first and second violins on opposite sides (violin I, cello, viola, violin II), rendering obvious the crossing of their parts in, for example, the opening of the finale to Tchaikovsky's Sixth Symphony.
In a typical stage set-up, the first and second violins, violas and cellos are seated by twos, a pair of performers sharing a stand being called a "desk", Each principal (or section leader) is usually on the "outside" of the first desk, that is, closest to the audience.