This paper examines privatization of Sensibility in Henry Mackenzie`s Julia de Roubigne focusing on the usage of its key words "trifles" and "trivial," which substitute for the word "private" that rarely appears in the novel, As writings "from crossroads of public and private," Eighteenth-century epistolary literature played the central role in the construction of the categories of public and private. Like Richardson`s epistolary novels, Julia de Roubigne consists of letter writings both as private testimony and public history. In contrast to Richardson, however, who idealizes the sincerity of female virtue legible between the lines of heroines` memoirs, Mackenzie makes his third and last novel to doubt the possibility of transmission of sensibility by suggesting the dark prospect of misreading Julia`s letters. I argue that impracticability of sympathy in this novel arose from privatization of Sensibility, which originally presupposed the idealistic synthesis of private and public virtue. In Julia de Roubigne, it is even aggravated by Montauban`s depreciation of "little world of sentiment" and his unreadiness to appreciate the more current and exchangeable value of "trifles." When the sentimental subjects cannot believe in the mutual connections made up through Sensibility, the calamities of conflict lead the sentimental novel to the "indulgence of strong emotionalism, moral polarization and schematization" of melodrama as Peter Brooks defined it.