You see it all over Washington, practice it in politics and academics, hear it in the English language, revive it in names like Helen and Julian. It’s THE CLASSICAL TRADITION (Harvard Univ., $49.95), and it’s all around us, in the architecture, the politics, the museums. Ancient Greece and Rome did more than leave us ruins to uncover—they established a living legacy on which Western civilization continues to build. To get a sense of how all-encompassing an influence this is, an international team of experts, headed by Anthony Grafton, Princeton professor of history and author of The Footnote; Glenn W.  Most, of the University of Chicago; and Salvatore Settis, of the Scuola Normale Superiore di Pisa, has compiled this rich encyclopedia. Organized alphabetically, the 500 authoritative articles cover all facets of Greek and Roman thought, from cartography and democracy to maxims and tragedy. Color and black-and-white images present the visual end of the spectrum, which runs the gamut from Palladio to I.M Pei, from the Pre-Raphaelites to Charles Addams.