Comments Elsewhere

https://blogs.stsci.edu/livio/2013/03/12/where-and-when-did-the-symbols-%E2%80%9C%E2%80%9D-and-%E2%80%9C%E2%80%93%E2%80%9D-originate/ “. . . The first use of the modern algebraic sign – appears in a German algebra manuscript from 1481 that was found in the Dresden Library. In a Latin manuscript from the same period (also in the Dresden Library), both symbols + and – appear. Johannes Widman is known to have examined and annotated both of those manuscripts. In 1489, in Leipzig, he published the first printed book (Mercantile Arithmetic) in which the two signs + and – occurred (Figure 1). The fact that Widman used the symbols as if they were generally known points to the possibility that they were derived from merchants’ practices.”