But the tides bring to the marsh and the island in it, to all shores that they touch here on our Atlantic seaboard, more than this. They bear deep in their emerald hearts, generated in their cool, clear depths, a rich vivific principle that bears vigor to all that they touch and sends rich emanations forth on the air beyond. Today on the inland hills and land-bound pastures the sun beat in sullen insolence and the wind from the west scorched and wilted the life in all things. The same wind, coming to me across two miles of salt marsh, had in its cool, salty aroma a life-giving principle that set the pulse to bounding and renewed vigor. It had gathered up from the marsh this tonic of the tides, this elixir vitae which all the doctors of the world have sought in vain. Some day some one of them, wiser than the rest, will distil its potency from the cool salt of sea tides, and humanity, poor hitherto, will find itself rich in possibilities of physical immortality. Sea captains have a foolish custom of settling down at eighty to enjoy life on shore, else there is no knowing how long they would live. They have breathed the aroma of this life-giving essence all their lives. Yet the sea itself is dead; it is a vast accumulation of the product of complete combustion, hydrogen burnt out. But just as dead worlds, which are the molecules of infinite space, shocking together, burst into spiral nebulae of flame which are the beginnings of live suns and planets and all luxuriant life thereon, so it seems as if the atoms of sea water, ever rushing to restless collision, burst continually into renewed life. All forms are in it, from the mightiest mammals to the protozoa which the microscope suspects rather than surely discovers. Every time molecule touches molecule in the depths, a new spark of tiny life must flare up, else never so many could inhabit the water. The coarser aggregations of these we see in bewildering profusion and variety every time the tides fall back and leave the rocks bare. At the bottom of the ebb I like to climb perilously down the rough Glades cliffs to life-brooding pools and inlets, where lazy waves swirl or are for a brief hour cut off. At the half-tide line the rock that is a reddish granite becomes chalky white with the shells of barnacles that cover every inch of space from there down. Acorn-like, they cluster closer than ever acorns did on the most prolific oak. After the tides reach them as they rise, the whole surface of the rock must be fuzzy with their curved cirri of tongues which protrude and lap the rising waves. Their number is legion, yet how infinite must be the fine floating life, so fine that we cannot note that it clouds the limpid water, on which these sessile gray creatures feed.