Starting with the main story made up of a third person dispassionate narrative then adding in letters at the end is exactly what we would find in scientific case studies
stevenson mixes the scientific journal and gothic fiction to display the theme of duality within the structure of the novel itself
scientific journal themes- dispassionate thrid person perspective through utterson and first person perspectives toeards the end to act as concret evidence (lanyon and jekyll)
Robert Louis Stevenson explained how he had long been trying to write a story on the subject of the dual nature of humanity
Stevenson wrote letters to friends about his childhood spending in bed suffering from dangerous fevers, and it was at this time he says that he really became aware of another person, another consciousness within him
Stevenson's use of oxymorons reflects the opposition of nature found in the characters of Jekyll and Hyde and also in his beliefs about the dual nature of humans