Sermo mirabilis: or the silent language [electronic resource] : Whereby one may learn perfectly in the space of six hours, how to impart his mind to his friend in any language, English, Latin, French, Dutch, &c. tho never so deep and dangerous a secret, without the least noise, word or voice; and without the knowledge of any in company. Being a wonderful art kept secret for several ages, in Padua, and now published only to the wise and prudent, who will not expose it, as a prostitute, to every foolish and ignorant fellow. / By Monsieur La Fin, once secretary to his eminence, the Cardinal of Richlieu. Licensed and entred according to order.