 The character Eugène de Rastignac had appeared as an old man in Balzac 's earlier philosophical fantasy novel La Peau de chagrin . While writing the first draft of Le Père Goriot , Balzac named the character " <unk> " , but he decided to use the same character from La Peau de chagrin . Other characters were changed in a similar fashion . It was his first structured use of recurring characters , a practice whose depth and rigor came to characterize his novels . 
