Reflecting the strong influence of Rousseau, Letters Written in Sweden, Norway, and Denmark shares the themes of the French philosopher's Reveries of a Solitary Walker (1782): "the search for the source of human happiness, the stoic rejection of material goods, the ecstatic embrace of nature, and the essential role of sentiment in understanding".
Reflectindo a forte influencia de Rousseau, Letters Written in Sweden, Norway, and Denmark comparte os temas de Les Rêveries du promeneur solitaire (1782) do filósofo francés: «A busca da fonte da felicidade humana, o rexeitamento estoico dos bens materiais, a aperta extática da natureza e o papel esencial do sentimento na comprensión».