From the 1890s until the 1960s, the location and orientation of stamps on postcards were used for the transmission of secret messages.
For all those who are in the situation of Hero and Leander, and similarly to them can only exchange secret signs about the feelings of their hearts, here we publish the secrets of the language of stamps. If the stamp stands upright in the upper right corner of the card or envelope, it means: I wish your friendship. Top right, across: Do you love me? Top right, upside down: Don’t write me any more. Top right, thwart: Write me immediately. Top right, upright [once more again???]: Your love makes me happy. Top left, across: My heart belongs to someone else. Top left, upright: I love you. Bottom left, across: Leave me alone in my grief. In line with the name: Accept my love. Same place, across: I wish to see you. Same place, upside down: I love someone else.