The air is crystalline and the sunlight through the pitch pine needles gives them a glassy sheen. This is one of those rare times when almost all of Cape Cod’s innumerable ponds are iced over and the children can go skating after school. It has been consistently cold for weeks, with comparatively little snow, and the pond surfaces tempt all skaters to soar. But we have had a day and a half of thawing weather. When my young daughter and I go to a pond to skate, we hear its fine whomping sound as it expands under the sun’s warmth. What looks like jagged broken bits of crystal, catching light on the surface, turn out to be part of the ice structure, thawing ice refrozen. We find hundreds of water spiders frozen in around the edge where yesterday they had been brought out into the water by rain and comparative warmth, and on the way we found a dead worm on top of frozen ground. So some animals are flung around with the season and respond fatally to chance. They belong to an allowance left over from December. Then it ends, and the day hardens like the ice. It is as though the helpless were not to be allowed their helplessness for some time to come. To skate on a long stretch of unmarked ice, over green reflected clouds, with the sound of clear air swishing past your face, is to voyage, full sail. It is a shining freedom, and our only competition is in play, to skid and turn and rush like water birds in the springtime--the only hardship a bruising fall. Under black holes we can see down to the bottom of the pond, where there are little forests of green moss and water plants, very still and soft. Suddenly a diving beetle swims quickly and erratically across and then a slow tadpole moves into sight. There is enough sun-induced warmth in the shallow water at the pond’s edge to allow life more play, though in that respect a pond is easier on its inhabitants than the land. With its cover of ice it is now in a state of “winter stagnation.” There are frogs buried in the mud and fish moving sluggishly in cold, stabilized waters. But this is an environment which always allows activity in at least some of its inhabitants throughout the year. Its extremes and revolutions of temperature bear little comparison with those of the land. Our hazards are of a sterner kind. When we kneel on the ice, where the mobile sky is reflected, and look down in, the water world seems half awake and half asleep, half tropical and half glacial. The waters are almost motionless over intermittent green carpets and through their black depths. The whole being of the pond seems to move independently of our surface storms. It has a heart of its own.