The air is usually considered as the great source of destruction to bodies, whether animal or vegetable; but we do not always understand by what means or in what manner it is performed. What we term destruction and decay of one substance, occasions the production and ripening a multitude of others; wherever the air is admitted, with it a thousand different things find their way; and what is usually attributed to the effects of that fluid, is in general occasioned by the multitudes of bodies with which it is fraught. Redi observed, that flesh preserved from the access of flies, would bread no maggots; and it is as constant an observation, that vegetable substances will keep a long time in whatever state they are, if the air be excluded; but as soon as it is admitted, they also produce or afford their several kinds either of animal, or minuter vegetable inhabitants. In the first of these cases, the parent flies make their way to the exposed flesh, and there deposit their eggs for the production of a new offspring; in the other, multitudes of the seeds of minute plants and ovula of animals are floating in the air, and accompany it wherever it enters; if they be thus deposited in a place proper for vegetation and accretion, they burst their inclosures, and attain their growth as regularly as the seeds of plants deposited in the earth, or the eggs of larger animals in the nest.
The same wisdom which placed the sun in the center of the system, and arranged the several planets around him in their order, has no less shewn itself in the provision made for the food and dwelling of every bird that roams in the air, and every beast that wanders in the desert; equally great in the smallest and in the most magnificent objects; in the star and in the insect; in the elephant and in the fly; in the beam that shines from heaven and in the grass that cloathes the ground. Nothing is overlooked, nothing is carelessly performed: every thing that exists is adapted with perfect symmetry to the end for which it was designed. This wisdom displayed by the Almighty in the creation, was not intended merely to gratify curiosity and to raise wonder; it ought to beget profound submission, and pious trust in every heart.