The author of this Latin treatise was a Belgian philosopher with a particular interest in Jewish mysticism. Here he sets forth the idea that Hebrew is the most suitable tongue for teaching the hearing impaired to speak, basing his theory on the idea that Hebrew is the “natural” language—the language spoken by Adam and Eve in the Garden of Eden—a notion also found in earlier sources, both Jewish and Christian. The book contains thirty-six copperplate engravings showing the parts of the mouth from which a particular Hebrew sound is produced.