These artistic/graphic design pieces by Massimo Vignelli demonstrate a good range of his creative work, with each example applying to a specific application that the field embraces. The Manhattan subway map, although self- explanatory, demonstrates the art of presenting neatly and systematically as doing so is important for relaying information to the masses in a clear and visually-friendly method.
The American flag is noteworthy for its composition: what looks to be newspaper articles and headlines (in sepia and photo-negative tone) make up the texture of the flag. If I need to guess, the inclusion of the text on the flag signifies the U.S. being a country proud of its mass publication industry and culture since the Revolutionary era.
Lastly, the poster above may seem generic but is interesting to note because Vignelli illustrates typography and use of even-spacing (or grids) to achieve the neat and organized format of the poster. Even the color is of good use as it demonstrates emphasis where needed, in this case being the highlight of the latter part of the quote. Furthermore, font size is used for the same part to illustrate even more of a striking effect.