Dr. Jekyll and Mr. Hyde

by Robert Louis Stevenson

Dr. Jekyll and Mr. Hyde: Foil 1 key example

Chapter 3
Explanation and Analysis—A Slyish Cast:

Despite their many physical differences, it is clear that Hyde is a manifestation of a hidden element of Jekyll. In this sense, they are foils for one another. This conclusion can be drawn from the initial description of Jekyll in the book: 

 [He was] a large, well-made, smooth-faced man of fifty, with something of a slyish cast perhaps, but every mark of capacity and kindness.