The project, entertained by Leibniz and others, of creating an ideal language to facilitate ratiocination, is investigated in detail. Six possible relations between the ideal language (IL) and the natural language (NL) it replaces are studied. (1) IL says exactly what NL says, but says it much more clearly. (2) IL says exactly what NL says, but does so more economically. (3) IL says exactly what NL says, but does so more succinctly. (4) IL says part of what NL says, (...) and says it more perspicuously. (5) IL says part of what NL says, and says it more perspicuously; moreover, there is an effective procedure for going from NL to IL. (6) IL says everything that NL says, plus some things that NL cannot say. (shrink)