Snowy (character) he is able to understand human language, and communicates with speech bubbles. His verbal responses to various situations include jokes, expressions of fright, and pleas to Tintin to exercise caution. In the early albums he takes an interest in mechanics and geography; in "Tintin in the Congo", he makes biblical references. As a dog, he also sniffs, tracks, chases, and bites. The character of Snowy evolved through the course of the Tintin series. In early works he exchanges dialog with other characters, including animals, and provides a running commentary on the situation. His character then became affected by the introduction
The Adventures of Tintin of heart: it is packed with close textual analysis and laden with psychological jargon." Following Apostolidès's work, French psychoanalyst Serge Tisseron examined the series in his books "Tintin et les Secrets de Famille" ("Tintin and the Family Secrets"), which was published in 1990, and "Tintin et le Secret d'Hergé" ("Tintin and Hergé's Secret"), published in 1993. The first English-language work of literary criticism devoted to the series was "Tintin and the Secret of Literature", written by the novelist Tom McCarthy and published in 2006. McCarthy compares Hergé's work with that of Aeschylus, Honoré de Balzac, Joseph Conrad, and Henry James