Compared with the new eukaryotes the old prokaryotes were little more than "bags of chemicals," in the words of the geologist Stephen Drury. Eukaryotes were bigger—eventually as much as ten thousand times bigger—than their simpler cousins, and carried as much as a thousand times more DNA. Gradually a system evolved in which life was dominated by two types of form—organisms that expel oxygen (like plants) and those that take it in (you and me).
地球已經朝著真正有意思的行星邁出了第一步。與新的真核細胞相比，舊的原核細胞——借用英國地質學家斯蒂芬·德魯里的話來說——不過是“幾囊化學物質”。真核細胞比它們比較簡單的堂兄弟要大——最后要大1萬售，能夠多帶1000倍的DNA。由于這些突破，生命漸漸變得復雜，結果創造了兩種生物——排斥氧的（比如植物）和接受氧的（比如你和我）。
Single-celled eukaryotes were once called protozoa ("pre-animals"), but that term is increasingly disdained. Today the common term for them is protists . Compared with the bacteria that had gone before, these new protists were wonders of design and sophistication. The simple amoeba, just one cell big and without any ambitions but to exist, contains 400 million bits of genetic information in its DNA—enough, as Carl Sagan noted, to fill eighty books of five hundred pages.
單細胞的真核細胞一度被稱做原生動物（意思是“動物之前”），但那個名稱越來越遭人鄙棄。今天，它們通常被叫做“原生生物”。與之前的細菌相比，原生生物在模式上和復雜程度上都是個奇跡，簡單的變形蟲只有一個細胞大，除了生存沒有別的雄心壯志，但在它的DNA中包含著4億條遺傳信息——正如卡爾·薩根指出的，足以寫出80本500頁的書。
Eventually the eukaryotes learned an even more singular trick. It took a long time—a billion years or so—but it was a good one when they mastered it. They learned to form together into complex multicellular beings. Thanks to this innovation, big, complicated, visible entities like us were possible. Planet Earth was ready to move on to its next ambitious phase.
最后，真核細胞學會了一種更加獨特的把戲。這花去了很長的時間——10億年左右，但它們一旦成為專家，那還是個挺不錯的把戲。它們學會了結合在一起，形成復雜的多細胞生物。由于這項新的發明，像我們這樣大而復雜的、可見的實體終于成為可能。地球這顆行星已經準備好進入下一個雄心勃勃的階段。
But before we get too excited about that, it is worth remembering that the world, as we are about to see, still belongs to the very small.
但是，在為此感到過分激動之前，應該記住，我們將會看到，世界仍然是小生物的世界。
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