In the great universe, to whatever part of it we turn, one controlling principle is ever apparent, one sentiment seems to pervade the whole—economy; and so forcibly does this strike the attention of every one of us, that we have expressed it in a proverb and use it as a motto, " Waste not, want not." The flowers are ever ready to receive the dew-drops, and when they have done with them, the morning sun evaporates and keeps them in the clouds ready for use again. Matter is indestructible, and although we can by fire and other means render it invisible, what is our surprise to find that it has assumed a gaseous form, and the piece of charcoal that we burned is now floating in the room mixed with the atmosphere we are breathing. Matter is ever changing. The forces of nature which we call chemical action, gravity, electricity, light, heat, and life are unceasingly effecting the transmutation of substances ; thus, for example, ages long since rolled away, myriads of little creatures with shells not larger than a pin's head, acted as the scavengers of the ocean, they died, and sunk to the bottom of the deep, and to-day we find their shells as chalk and limestone all over the world, and naturalists tell us that on the sea bottom of the Gulf of Mexico, and in various parts of the Gulf Stream, there are limestone beds being formed by the modern representatives ef ancient Foraminifera. The lovely tints that deck the leaves in the Fall, and give to our autumnal scenery such a distinctive beauty, is due to some bed of iron ore, which has lain hidden beneath the rocks for centuries. Some little brook first found it out, and carrying it away bit by bit has spread it over the soil, gradually the iron ore crumbles, and the winds' disperse it, the trees feed upon it, and in the autumn it shows that it is there, by the color of the leaves. When trees shall have decayed, and what is now dry land shall have been depressed and upheaved, covered by the sea and scorched by the sun, who knows but that that same iron may form a nodule or ball in a bed of coal, and be worked and smelted for the use of man. All these changes work together harmoniously. All goes on in exact proportions. No waste, no want! "What is one man's meat is another's poison" is another maxim which the economy of nature teaches, and one simple illustration will quickly make it plain. The solid portion of living things, if we except the skeleton, is carbon—charcoal. This all animals must have in their food, and from the food the digestive organs take as much as is necessary to make muscle, flesh and tissue, throwing the rest away from the lungs as an invisible gas, poisonous and deadly. When we for a moment think of the number of beings who are every moment breathing into the common atmosphere such vast quantities of this gas, and have been doing it for centuries, we ask, " How is it, then, that we can live ?" In the quiet and still night when men and animals sleep, the plants are greedily and eagerly absorbing all this carbonic acid, and with care taking every particle of carbon for their own nourishment, they throw off as useless that which is most necessary to the support of" animal life—oxygen. So the proverb is illustrated, for what is the poison of the animal is the food of the plant. In this way, lessons may be learned by studying the workings of the natural forces, and by imitating the economy of nature, we shall ever be healthy, happy and content.