Book excerpt: Linked by the events of Bernard Knox's remarkable life, the twenty-five chapters of "Essays Ancient and Modern" cover subjects ranging from Hesiod, Homer, and Thucydides to Auden, Forster, and the Spanish Civil War. With a masterful eye for the telling detail, Knox continually reminds us that we share the present with antiquity's living past. A soldier in Italy finds a battered book in the rubble of a bombed-out firehouse-- and opens it to read Virgil's denunciation of war. An illiterate Greek bard composes a garbled Homeric song to celebrate the recent heroism of local partisans. A traveler heading north from modern Athens must choose between the Sacred Way-- or the NATO Road.