If we are interested in the communication of mathematics (or better: of mathematical understanding) and think of a very simple model consisting of a sender, a message and a receiver then hermeneutics is dealing with the part of the receiver. The massage might be intended or not, the important thing is that it is considered by the receiver as a message. This message has to be interpreted (which means: translated) which induces a difference (big or small) between the code of the message and the codes at the disposal of the receiver. It is even not clear if the code ascribed to the message reveals the actual code of the sender. Mathematics (and especially the part of it called logic) is the science which tries to avoid this problem of interpretation but since humans are involved it cannot be successful. To show this is the main aim of this encyclopedia.