mains a merciful beacon to others; who may learn, from his doom, that there is a Power which can say, as easily to the tempestuous ocean of ambition, as to the natural deep, "Hitherto shalt thou come but no further: and here shall thy proud waves be stayed."

CHAPTER VI.

ADAPTATION OF THE ATMOSPHERE TO THE WANTS OF MAN.

SECTION I.

The general Constitution of the Atmosphere.

IN the foregoing part of this treatise the physical condition of man has been considered under the view of the general capabilities of his nature, rather than of his actual state; but it is evident on a moment's reflection that his actual state will be very different at different periods of time, or in different parts of the world at the same period: and this observation applies no less to communities than to individuals. How great the contrast, with reference to the case of individuals, between the intellectual powers and attainments of a Newton and a native of New Holland; and in the case of communities, how great the contrast between any of the kingdoms of modern Europe, and the rude tribes from whence they were originally derived.

In proceeding then to illustrate the adaptation of the external world to the physical condition of the human species, we must view individuals or communities under all possible circumstances of existence, and make the illustration of as general application as the nature of the subject evidently demands.

And, in order to effect something like a systematic arrangement of the immense mass of materials whence the following illustration is to be deduced,

it is proposed to investigate separately the four kingdoms or divisions of nature, the general characters of which were given in the commencement of this treatise; beginning with the atmospherical and ending with the animal kingdom.

If it were possible, with the bodily as with the mental eye, to behold the constitution of the atmosphere which surrounds our earth, we should view a compound probably the most complex in nature: for into this circumambient ocean of air, as it is called by Lucretius,* are carried up whatever exhalations arise not only from the earth itself, but from every organized form of matter whether living or in a state of decomposition that is found upon the earth's surface; the dews of morning, the balms of evening, the fragrance of every plant and flower; the breath and characteristic odour of every animal; the vapour invisibly arising from the surface of the whole ocean and its tributary streams; and, lastly, those circumscribed and baneful effluvia, however generated, which when confined to definite portions of the atmosphere produce those various forms of fever which infest particular districts: or those more awful and mysterious miasmata, which, arise in some distant region, and advancing by a slow but certain march, carry terror and death to the inhabitants of another hemisphere.

Such is the complex character of the atmosphere; and, indeed, from this assemblage of vapours contained in it, it has received its peculiar appellation; being the receptacle, or magazine, as it were, of terrestrial exhalations.†

All these various exhalations however may be considered as foreign to the constitution of the air, being neither constantly nor necessarily present anywhere; all, with the exception of that aqueous vapour which

"Semper enim quodcunque fluit de rebus; id omne
Aeris in magnum fertur mare.'

Liq. v. 277, S.

is continually rising from the surface of the earth, as well as of the ocean and every lake and river. But, in addition to this aqueous vapour, the air is also charged to a variable extent with light and heat and electricity; of which the two first are so obviously adapted to the wants of man as to demand immediate attention. Electricity is probably of equal importance in its relation to man: but the true character of that relation has not yet been sufficiently developed to call for a distinct consideration on the present occasion.

SECTION II.

Light.

THE metaphorical expressions of all ages and notions, with respect to light, sufficiently evince the value in which that inestimable gift is held. In the sacred Scriptures indeed, not only are temporal blessings compared to light, and temporal evils to darkness; but holy deeds are frequently described under the character of the former; and unholy deeds under the character of the latter: and, with respect either to classical or oriental literature, a thousand instances might easily be adduced illustrative of the same metaphorical use of the terms in question.

When, after a dark and temyestuous night, the mariner first perceives the dawn of returning day; although that dawn discover to his view the evil plight to which the storm has reduced his vessel, why does he still hail day's harbinger as his greates relief, but because without the aid of light he could not possibly extricate himself from the difficulties of his situation? Or, when the child, awakened from its sleep, finds itself alone in darkness, why is it overwhelmed with terror, and why does it call out for protection, but from the influence of those undefined fears, which naturally occur to the mind under the privation of light?

There is something so congenial' to our nature in light, something so repulsive in darkness, that, probably on this ground alone, the very aspect of inanimate things is instinctively either grateful or the reverse, in consequence of our being reminded by that aspect of the one or of the other: so that on this principle, perhaps, particular colours throughout every province of nature are more or less acceptable in proportion as they approach nearest or recede farthest from the character of light, whether reflected immediately from the heavenly bodies, or from the azure of the sky, or from the thousand brilliant hues with which the setting or the rising sun illuminates its attendant clouds.

In illustration of the principle just advanced, gold and silver among metals might be opposed to lead and iron; the lily, or the rose, to the lurid aspect of henbane or belladonna. And though something of a moral character may in these instances determine the preference; yet there is.nothing unreasonable in supposing, that as the instincts of the inferior animals regulate their tastes and distastes to natural objects, so there may also be in the case of human beings congruities, or the reverse, between the sense impressed and the object impressing it. In fact with respect to that sense, the organ of which is the ear, it is known that infants shrink back from deep sounds, and express delight at acute sounds, long before any intellectual or moral feeling can sway them; and, correspondently with this assertion, the lullaby of the nurse partakes, among all nations, of the same essential character, It is a fact equally deducible from observation, that particular flavours and odours are naturally acceptable or the reverse, to children. And again, with reference to the sense of touch, smooth surfaces almost universally give a pleasing impression; which is not imparted by rugged surfaces. Why then may it not be the same with respect

to the sense of sight, in the case either of colour or of form?

The abundant supply of light from its natural source the sun, and the ease with which it is producible by artificial means during the absence of that luminary, render us habitually less sensible of its real value, than undoubtedly we should be, were we to experience a long continued privation of it.

to the regularly periodical privation of it which we experience in consequence of the alternation of night with day, this is so far from being an evil, that it is obviously beneficial; inasmuch as, in consequence of this very absence sleep is both directly and indirectly conciliated: without which gift of Heaven, all our faculties would soon be exhausted, and all our happiness consequently extinguished.

The beneficial influence of sleep on our whole frame is too obvious in its effects to require any formal demonstration: but it will be interesting to consider its relation to the absence of light. It appears then that, by a fundamental law of our nature, a sense of uneasiness invariably follows a long continued exercise of our powers, either corporeal or mental: and, unless this sense of uneasiness have been produced by too inordinate exercise, it is soon relieved by that state of the system which we call sleep; during the continuance of which, provided it be sound and of a prfectly healthy character, all the voluntary muscles of the body become relaxed, and the nervous system remains comparatively inactive; the whole body acquiring by this temporary cessation of its energies a renovated accumulation of those powers, which are necessary for the purposes of active and intellectual life.

In order to dispose us to yield to the sensation of approaching sleep, the periodical succession of night to day has been ordained by nature. For, with the approach of darkness cease all the usual stimuli of that sense, which is accommodated to the impulse of light, and which calls our faculties into action more ་