The point of the book is unlike any other reference book I've seen: It's an etymology of ideas, intended to show us that the majority of our modern-day concepts have sturdy roots that stretch back to the classics. Do you want to brush up on the impact of the Orpheus story? It's all here, from Rilke to the Maori to Sartre, including just about every serious scholarly interpretation of the myth over the last 2000 years, in plain English. You can find the history of censorship, the way portrayals of the plague have changed with the birth of modern medicine, and an essay about the importance of biographies over the millenia.
From that last chosen-at-random example, here are some sample sentences: "Andre Maurois...commented perceptively that biography shares with tragedy a sense of magnificent inevitability that the novel generally lacks. This may account for the equal success of accounts of lives that ended badly and those that ended well. For all its many transmutations, the classical roots of the genre still lie visible below the surface and can be found, acknowledged or not, in so homespun a life-writer as the mid-19th-century journalistic biographer James Parton..." The entries wander everywhere, pausing regularly to tie things back to their most elemental form, to remind you that others were here before, and they felt the same way you did. You can explore the book at Google Books.
It's refreshing to find a reference work like this, a text so obviously obsessed with the past. While it may not hold much practical use for non-academics, it's a book that gloriously rewards the casual browser with a continuous stream of gems. It's a perfect book to plant your feet on solid ground if you're feeling as though history has lost its mooring; this has all happened before, The Classical Tradition assures you, and it will happen again. And that's exactly how it should be.