  Ever since Werner Heisenberg's 1927 paper on uncertainty, there has been
considerable hesitancy in simultaneously considering positions and momenta in
quantum contexts, since these are incompatible observables. But this persistent
discomfort with addressing positions and momenta jointly in the quantum world
is not really warranted, as was first fully appreciated by Hilbrand Groenewold
and Jos\'e Moyal in the 1940s. While the formalism for quantum mechanics in
phase space was wholly cast at that time, it was not completely understood nor
widely known --- much less generally accepted --- until the late 20th century.
