I watched the swash marks. The swash of the surf full of sand rushed up the beach, cleared suddenly, and retreated, leaving a ridge along the beach. This elevation became the tide limit, and a new series started lower down. The swashes couldn’t climb over the ridge because the tide was going out. And so for hours ridge after ridge was built. I watched high-tide scallops, six feet apart, forming heaps at the top of the beach. The swash waves ran into the bays between the heaps during the flood hours, making a rush up and a suck down. The rush up was muddy, the suck down was clear. Pebbles and sand were building up on the sides of the small promontories. Each heap was horseshoe-shaped, with the toe seaward. Forty or fifty crescents got smaller and more sandy toward the middle of the beach. Here was rhythmic force making repetition. The ripples and swash marks were repeated seaward. Clearly the headland of rock was making pebbles and sand, sending pulsations along the beach, instead of across it. The ripplemarks were packed sand of the low-tide flat, formed totally under water parallel to the waves. The back-and-forth motion of waves made a pattern of sweep and eddy on the bottom. Were beaches, then, things of habit like birds? Here were four kinds of sand waves, all on one beach, all of them complicated by wind and water and tide; big and little; shapely and regular. The beach was alive. It was building from the end, it was rippling under wave action. It fed the wind as it dried, and the wind made an exquisite dune pattern of the grains. Perhaps beaches might be natural history, just as much as the birds that inspired my interest in nature when I was eight years old. The mystery of the beaches drove me to a new discovery; to the university library, where I found French and English references to ripplemarks. I found experiments, soundings, fossil sandstone ripples. I learned that such great authors as the botanist De Candolle and Sir George Darwin had interested themselves profoundly in what happened to the sand grains. From the library I went to mud puddles in a tank and to experimentation. Thus I found my way from beach to books and from books to the making of baby beaches. Later, at Harvard, zoology and botany were all cells and embryos and the microscope. The habits of animals scarcely entered into our studies. The natural history of Audubon and my boyhood had vanished. The new words were phylogeny and cytology, development of the individual, and cell development. So in mineralogy the microscope and the tiny crystal governed; the molecules of the crystal, and the chemical atoms of the molecule. Science was headed toward the infinitely little, though later, by way of the spectroscope, it was to leap to the infinitely big of the heavens. I never learned to think the universe finite.