Ever since Galileo's time, scientists have been interested in how to create a perfect language capable of supporting communication at a horizontal level i.e. within the scientific community, and at a vertical level, i.e. between scientists and the public. Special attention will be spent on the mathematicians' role, especially Giuseppe Peano's. The Italian mathematician played a leading role in the creation of a perfect language, both at a horizontal and a vertical level. On the one hand, there is his successful attempt to introduce a standard logical and symbolic system of notation, which became essential for communication among mathematicians. On the other hand, there is the complete failure of his ambitious Latino sine flexione (Latin without inflection), a perfect language which died with its creator.