"Bingley has never met with pleasanter people or prettier girls in his life . . . Darcy, on the contrary, has seen a collection of people in whom there was little beaity and no fashion, for none of whom he had felt the smallest interest..." (pg. 18)
In this passage, Austen uses foil to contrasts the views of Bingly and Darcy about the ball at Meryton Town Hall. This shows the drastically different personalities of each young man. While Bingley is open and inviting, Darcy is cold and austere. These two personalities are extremely important to the plot of Pride and Prejudice-- Darcy's harsh exterior is one of the main things that causes Liz to judge him and Bingly's openess is an important part of his relationship with Jane.