The aim of this study is to show the process Father Athanasius Kircher (1602-1680) used to translate Egyptian hieroglyphic texts. Rejecting any link between script and language, Kircher would interpret hieroglyphs as a collection of symbols whose meanings were to be discovered. In his quest, he relied on the writings of classical and Christian authors, mainly those who belonged to the neo-Platonic school (Plotinus, Porphyrus, and Jamblichus). Kircher also used some esoteric texts like the Hermetic treatises and the writings of Jewish and Arabic Kabbalists. Kircher’s studies must be judged against his theologian conception as he was convinced that there existed an unbroken tradition from the first Adamic revelation down to the teaching of the Bible. This tradition admittedly left many traces in ancient civilisations (prisca theologia). In this reconstruction, widely supported in the Renaissance and the Modern Times, Egypt was supposed to play a significant and pivotal role.