of this gravity; for, possessing weight itself, it would rather retard the velocity of falling bodies. We must, therefore, look for the cause elsewhere. Perhaps the opinion approaching nearest to truth, is that which supposes the earth has the property of attracting bodies placed at a certain distance. Or perhaps we may impute the cause of gravity to some foreign matter distributed through all bodies.

But though we cannot exactly ascertain its cause, nothing is more clear than the advantages which result from it. Without the power of gravity we should not be able to move as we do. Our centre of gravity is about the middle of our bodies; when we raise the right foot, we must bear this centre upon our left. If we bend our body forward, we are in danger of falling; but, by extending our right leg, we prevent our fall and make a step. Thus our walking is in some measure a continual series of interrupted falls. Hence, when we ascend a hill, we bend our body forward; and backward when we descend. In carrying a burden on our shoulders we incline forwards, and lean back when we carry it in our arms. All this proceeds from the laws of gravity, which regulate the motions of animals, when they walk, swim, or fly.

The same laws are also extended to the heavenly bodies. The sun attracts the planets, and each planet attracts its satellites; or, what is the same thing, the planets gravitate towards the sun, and the satellites towards the planets; for a body made to revolve in a circle would always fly off from the centre in a right line, if it met with no obstruction. The planets revolve in their orbits with the greatest velocity. It seems as if a motion as rapid as that of the moon should whirl her from us to an immense distance in the immeasurable space, if there was not force which continually impelled her towards our globe, and which was strong enough to counteract the force tending to propel her from the earth. And this force is the gravitation of the moon towards the earth. If our earth was either lighter or heavier than it is, it would approach too near to, or fly off too far from, the sun in the one case, nobody could support the heat; in the other cold would be equally unbearable: either every thing upon the globe would be consuined by heat, or frozen by excess of cold.

Here again we have fresh cause to admire and adore that Wisdom, which, by means apparently so simple, regulates the motions of animals, and wields the vast globes that roll in the firmament. By the laws of gravity alone the smallest particles of dust are prevented from being lost, either from our earth, or from any of the globes which continually revolve around us. We here see the greatness of that power and wisdom which produce the most astonishing effects by means which appear to us the most insignificant.

JULY XXVIII.

MANY EFFECTS IN NATURE PROCEED FROM THE SAME CAUSE.

Universal nature is an endless chain of causes and effects; and as all parts of the universe bear a relation to each other, every motion and every event depends upon a preceding cause, and itself becomes the cause of effects which follow its action. The whole constitution of the world is well calculated to convince us that it is not chance, but a divine Wisdom surpassing all conception, which first erected this wonderful edifice, impressed motion upon its different parts, and determined the great chain of events to depend upon and succeed each other with order and regularity. It is not difficult to acquire this degree of knowledge; for though our acquaintance with nature is very limited, we yet are able to perceive that many important effects depend upon causes evident to human intelligence. As a proof of this we may instance many natural phenomena.

What a variety of effects are produced by the heat of the sun! It not only contributes to the life of an innumerable multitude of animals, but also to the vegetation of plants; to the ripening of seeds and fruits; the fluidity of water; the elevation of vapours; and to the formation of clouds, without which we should have neither rain nor dew.

The air also is so constituted as to answer various ends. By means of this element, animals are preserved alive, and all the vital functions performed with vigour. It is by means of the air that the fire burns, and combustion is supported; that sound is conveyed in undulations to the ear; that winged creatures fly from place to place; and that man traverses the vast extent of the ocean. It is the air which supports the clouds, till, becoming too heavy, they fall in rain; it is that which prolongs our day by means of the twilight; and without air the gifts of speech and of hearing would be useless. All these, and many other advantages, depend upon the air in which we live and breathe. Is not then this wonderful element, which surrounds our globe, and is too subtile for our eyes to behold, and yet so strong that nothing can resist its force, a most evident proof of the wisdom of God?

The power of gravitation existing in all bodies, preserves the mountains in their places, restrains the ocean within his depths, and keeps the earth within her prescribed orbit; supports every created being in its proper place in nature; and prescribes to the stars of heaven the course they are to observe.

Who can enumerate the various uses of water? It serves to dilute, to soften, to dissolve, and mix, many substances which we could not otherwise use. It constitutes a most wholesome beverage, is the chief nourisher of plants, sets in motion mills and other machines, is the habitation of fish, and bears upon its surface treasures from the four quarters of the globe.

How varied and numerous are the effects of fire! And it is not only in the natural world that we see many diversified effects proceed from the same cause; in the moral world we also often see a single disposition of the mind produce effects not less various. Let us take for example the natural inclination which prompts us to love our fellow-creatures. From this are derived the solicitude of parents for their children; social union; the bonds of amity; patriotism; goodness in those who govern, and fidelity in those who obey. Thus a single propensity keeps each individual in the circle prescribed for him; becomes the bond of civil society; and is the principle of virtuous actions, laudable enterprises, and innocent recreations. All this furnishes the most evident proof that the world is not made by accident, nor the materials which compose it put together by chance, without relation or connexion between each other; but, on the contrary, that it forms a regular whole, which the divine Power has ordered with infinite wisdom; and in every phenomenon of the visible world some rays of this ineffable wisdom blaze forth, and declare the unutterable goodness of God.

JULY XXIX.

OF SOME DISEASES OF PLANTS.

Vegetables are subject to many diseases. Sometimes they are covered with a white matter which sticks to them like dust, and is called mildew. This does not happen from insects, as is commonly believed; but from a stagnation in the juices, and a beginning of corruption, which attracts insects, and invites them to deposite their eggs. The stagnation of the juices is the first stage of corruption; and it is supposed that that alone is sufficient to attract insects, because they are seen to swarm by millions as soon as, from whatever cause, natural or artificial, the circulation of juices in a tree is stopped. Hence the feeblest trees, and those exposed in unfavourable situations, are the most subject to this malady. If insects were really the cause of it, it could not be produced by art; whereas, if a tree is purposely wounded, or deprived of the care it requires, it will become subject to the mildew. And upon this tree, so weakened, immediately are seen thousands of insects, whilst the neighbouring trees are free from them. Hence this corruption is no more owing to insects, than is the decay of animal substances; we must look for the cause of it in the obstruction of the juices, which may be occasioned by many circum

stances.

A matter resembling dew, but which is glutinous, sweet, and acrid, frequently destroys plants. It has been thought that insects conveyed this glutinous juice into vegetables, or that bees had deposited honey upon them. But frequent observations have demonstrated that this matter falls from the air in form of dew. In certain coun

tries it is deposited in small drops upon a great variety of different vegetables; and in the space of a single night it will cover alinest all the leaves of a long row of trees, upon which it had not been before perceived. Perhaps this dew may be formed from the exhalations which arise from flowers and blossoming trees, out of which the bees extract their honey; and if more is deposited in one place than in another, it is owing to the direction of the wind. Perhaps also it may be the effect of some disease in the plants from their juices being vitiated; for it is the branches, leaves, bushes, and weakest trees, that are most subject to this disease. It is also remarked, that the leaves upon which this species of dew falls become spotted and black, and soon spoil; most probably this substance is the cause of it.

Here we find evident traces of divine Wisdom; for, since insects require nourishment, it is advantageous to us that they are directed to obtain it from those vegetables which, being already spoiled, are become useless, if not prejudicial to us. And this is a new proof of the particular provision which God made for man when he established the world. It is owing to this arrangement that these insects take nothing that is necessary for our support; but on the contrary attach themselves to that which would be destructive to us. In the wise economy of Nature, each plant, tree, and animal, serves for the support of different creatures.

JULY XXX.

MEANS OF SUBSISTENCE WHICH NATURE PROVIDES FOR ANIMALS.

It is a great proof of the goodness and supreme power of the Almighty, that there is every where provided a sufficiency of aliment for all the living creatures with which the world is filled. It is not indeed wonderful that the countries which lie within the temperate zones should supply their inhabitants with a sufficiency of nourishment; but that this should be the case in all places, even where we had least reason to expect it, and that the necessary provisions never fail to so many species of animals, can only be attributed to the cares of a beneficent and all-wise Providence. He has proportioned the supply of provisions to the number and wants of the animals which are to consume them. In most places there is a superabundance; but this profusion is not so great as to cause the alimentary matter to spoil or decay, for that would be prejudicial to the world.

Among the many articles of nourishment, those which are most useful and necessary are generally found in the greatest abundance, and multiply the most readily. As there are a great number of animals which only live upon herbs, the meadows abound with them and the most wholesome plants, that grow spontaneously without the least culture, and easily resist the inclemency of the air. It is also highly worthy of attention, that corn, which is such a great source of

food for man, can be cultivated with so little trouble, and increase so astonishingly.

It is also a wise regulation of the Creator, that the taste of animals is so varied, that some love to feed upon herbs and corn, some upon flesh, others upon insects, &c.; some are content with a little, others are very rapacious. If all species of animals had an inclination for the same kind of food, the earth would soon become incapable of satisfying their wants, and would presently be converted into a vast desert. The diversity of taste then that we find among animals is a certain proof that it is not by accident that they prefer any particular kind of food, but from a particular instinct implanted by nature, which leads them to those aliments best adapted to them. By this means all the productions of the earth and of the sea are properly distributed; not only every thing which breathes is amply provided for, but those substances which, becoming putrid, might be prejudicial, have their particular uses. For the wholesome plants would perish; the carcasses of birds, fish, and animals, would exhale the most poisonous effluvia; but that it has pleased the all-wise Creator to implant in animals an inclination for these different substances, which furnish them with an agreeable aliment.

Nutritious matters offer themselves spontaneously to the greater part of animals; they must therefore possess great skill in discerning them, and must employ great precaution in their choice. They are so constituted, that what is highly nourishing to one species, is injurious and sometimes poisonous to another. From the experiments and observations of botanists, it appears that oxen eat of two hundred and seventy-six species of grass, and reject two hundred and eighteen; that goats eat of four hundred and forty-nine, and leave untouched one hundred and twenty-six; that sheep feed upon three hundred and eighty-seven, and there are one hundred and forty-one which they will not feed upon; that the horse eats of two hundred and sixty-two, and refuses two hundred and twelve. Some animals are obliged to go to a great distance in search of nourishment; and obtain it with much labour, by digging for it in the earth, or collecting it from various parts where it is thinly scattered. Some choose the dead of night to satisfy their hunger in safety; others obtain their food by separating the grain from its husks, bruising them if hard; and some swallow small stones to assist them in digesting. Many would perish if they did not carry provisions into their nests against a future time of need. Others take their prey by having recourse to wiles and cunning, by laying snares, and by digging holes in the ground; and some pursue their prey in the air, in water, and upon land.

The more diversified is the food of animals, and their manner of procuring it, the more admirable is the wisdom and goodness of God displayed in their preservation. Let us then reflect upon the glorious perfections of our Heavenly Father; for the occasions which we find to magnify his name are more frequent than the day.