As Elizabeth refuses to join Mr. Darcy and the Bingley sisters on a walk outside, she subtly alludes to William Gilpin ideology of picturesque. Gilpin was a clergymen who lived during Austin's time. He was a painter and wrote well regarded essays claiming that picturesque was an image that looked perfect on paper. Elizabeth sees the Bingley sisters and especially MR. Darcy as proud. Elizabeth adds this allusion to subtly pronounce that their party it only perfect on the surface.
~"William Gilpin (clergyman) -." Biography Research Guide. 03 Apr. 2009