Many people have the idea, perhaps because of a human fascination with violent events, that nature is compounded of just such rigidities--dog eat dog, or tiger eat horse--or obversely, that nothing happens at all. Nature is either a menace or a great bore. Could I expect, going to some pond or water hole concentrated with life to find all kinds of mutual slaughter going on? At the edge of any small pond I see action enough this time of year. Many tadpoles hurry off in all directions at my footfall. I hear a bullfrog’s noble plucked bass sounding among the pickerel weed, while dark gray catbirds cry in thickets along the shore. A great antediluvian animal, a snapping turtle, with a fat black shell, a thick, fat head and neck, and large lidded eyes like a dog, climbs out of the water to lay its eggs on a sandy bank above. Its movements are slow and massive, each leg lifted as it goes. Only a sudden, lunging, upward snap as I tease it with a stick, shows what quick ferocity it is capable of. In the still pond waters there are schools of tiny, newly hatched fish, big-eyed, big-headed, with minute pin-sized bodies, running and twitching in rhythmic solidarity. A yellow perch runs by, and then a horned pout roves through the fry with apparent disregard. It passes near a sunfish nest, a little round, cleared depression on the bottom. The sunfish sallies after it in a short dash and then returns to hover over its nest, its fringed tail waving gently. In spite of our expectations, any aggression here is latent rather than actual, and need, it is clear, has room and time to spare. Co-ordination is intrinsic to the life of an environment, acted upon by every predator. There will be no fight between the sunfish and the horned pout, but the sunfish has affirmed its ancient rights to the territory that comprises its nest. It is bold in defense of its home, up to the point, presumably, that it goes beyond a boundary which its feelings establish for it. I am reminded of those birds, like the herring gulls and their “threat postures” (described by N. K. Tinbergen in _The Herring Gull’s World_, 1954) assumed when two birds defend their respective positions on either side of a boundary invisible to us but strongly felt by them. In these cases a fight may never result, because the two alternate drives of defense and aggression cancel each other out. What the trained observer sees as an indication of what is going on are “behavior patterns,” types of physical action that show him what this gull communication might mean. In any case, up and down the scale of life is force and counterforce, action and reaction, in a balance that is understood in as many ways as there are species.