In that valley where the alewives run, a narrow cut between low hills once made by melt waters from a glacier, and joining fresh-water ponds to Cape Cod Bay, there is now such a variety of life in such a variety of places as to challenge travel in all the senses. It reaches from the fresh-water ponds with their muddy shallows where pickerel weed begins to put up its stalks, painted turtles sun themselves on rocks out of the water, and sunfish make their nests along the sandy edges--from the pond waters gently lapping and smooth surfaces skidded by the wind--all the way through tidal marshes to the sea whose massive motion stands beyond us. Each area, first the ponds, then the brook, as it cascades down rocky slopes, turning as it winds through valley reaches into a creek, and then a tidal estuary, meeting the sand flats on the bay shore, each definite part of land or shore, has its newly active, co-ordinated riches. In the upper end of the valley, just below the pond outlet where fish ladders are crowded with migrating alewives, there is a wild and loud screaming of gulls. They wheel constantly over the stream, and crowds of them settle down on the water, quarreling over feasts of fish. Below them, black-crowned night herons bob and stand tall in a grove of pitch pines. When startled, they cluck and squawk like so many women over a scandal. When one of them flies too close to the herring gulls, it is chased away. Two upland plovers skim in fast, crying high. A black duck whirs up, showing the white under its wings. The land at the edge of the marsh is full of yellowthroats, warblers with a quick, slurred call: “Weewiticha, weewiticha, weewiticha,” as it sounds to me, and sometimes a softer “Chichibee, chichibee, chichibee.” I watch one of these trim birds. It has a yellow breast and yellow head masked distinctively with black. It lands in the leaves, whips around, flits, quick and alert. Its colors fit with shade and sunlight as though it had been conceived with them--a definite dash of light. In the stream, as it winds down toward salt water, subject to the rise and fall of the tide, small groups of alewives run quickly and persistently through the weaving currents, heading up toward gulls and then the nets and fishways beyond. I feel energy and motion demanding me. Seen or unseen, a flying, starting, striding, swimming, and inviting, makes of the present and its short lives an endlessness.