Like the tortoise, the apple exists both in the past and the present. In the present, Gus gives Hannah the apple. In the past, Septimus begins to eat it, and Thomasina declares her intention to write a formula that will describe the leaf. In the present once more, Valentine explains to Hannah that an iterated algorithm could describe the leaf’s general form, though not its exact shape. There are certain parameters of order in nature, within which disorder works out the specifics. The apple and leaf become a perfect example of how Thomasina brings together Enlightenment and Romantic thought. She loves math and geometry, but she applies those Enlightenment techniques to a very Romantic subject, namely natural forms. And she and Valentine show that both order (Enlightenment) and chaos (Romanticism) command the world.