no part of knowledge could be left to be our own acquisition by observation and reasoning. For what does not the intuitive knowledge, necessary to be our warner of dangerous applications or approaches to our bodies, include in it? It plainly comprehends in it an intuitive knowledge of our own body, and of all surrounding<73> objects to the influences of which it is exposed: that is, it comprehends an intuitive knowledge of the whole of nature. And consequently, having such knowledge (could we, or any creatures possibly have it, as ’tis plain from the nature of knowledge we cannot) is absolutely inconsistent with the dependence of any part of the knowledge of nature upon ourselves; or with such knowledge being in any degree our own acquisition; that is, with any thing’s being left to be matter of observation and enquiry to us, or subject of exercise to our reason. All parts of natural or real knowledge are so connected together and involved in one another, that if any part of it were attainable by us otherwise than it now is, no part of it could be attainable, as it now is, i.e. by induction, and by reasoning from properties so discovered. And would we not thus be deprived of one of our pleasantest and noblest employments and acquisitions?
From the necessity there is, that bodily appetites should be attended with uneasy sensations arises the necessity of all the other uneasy sensations accompanying our desires which are called Passions.
IV. Thus then we see the fitness of our being admonished by uneasy sensations of dangers to our bodies of bodily necessities and wants: because thus we are directed and impelled to relieve and preserve ourselves in such a manner, that reason, neither hath, on the one hand, little or no employment; nor, on the other, a very disagreeable and almost insurmountable task. But it is well observed by an excellent philosopher on this head, that when a necessity of adding strong uneasy sensations to one class of appetites appears, there must appear also a like necessity of strengthning the rest in the same mind by like sensations, to keep a just ballance.32 And thus accordingly, our bodily appetites being for good reasons accompanied with uneasy sensations, our moral desires and affections are strengthened in like manner by uneasy strong sensations to maintain a just balance; so is plainly the Στοργη or natural affection to children, so is compassion or pity to the distressed, and many other moral<74> passions, that thus the public and social ones might not be too weak and feeble in proportion to those which terminate more directly and immediately in the preservation or gratification of our senses. In a constitution, where one degree of force is requisite, a proportionate degree of force in other parts becomes also necessary; otherwise the constituent parts would not bear that proportion to one another, which an equal and sound balance in the whole requires. It is the same here as with regard to antagonist muscles to counterpoise one another in the body.a
The laws of matter make an infant state of body necessary.
And the law of progressive perfection makes infant minds necessary.
V. Let me just add upon this head, that as for our coming into the world by the way of propagation we now do, and with weak, necessitous, infant bodies: It is a necessary result of the constitution of this material world to which we are related by our bodies; and besides the many good effects of it of the social kind which are very evident, “There is an absolute fitness, that beings made for progress in knowledge, and in every perfection by their own application and industry conjointly with assistances from society, and who consequently must enter upon the world with infant minds, should likewise enter upon it with infant bodies.” How very unequally otherwise would our bodies and minds be yoked? How improper companions and mates would they be? As for death, what may be inferred concerning it, shall be considered, when having enquired into all the other principal laws relative to our present state, we are able to take a complete view of it. In the mean time, it is obvious, that death, or the dissolution of our bodily texture, in whatever way it happens, is always the result of our subjection to some of the laws of matter and motion, to which our union with the sensible world necessarily subjects<75> us, and to which are owing all the pleasures we receive from it in our present embodied state.
The dependence of mental powers and dispositions on the body.
A great variety in respect of these among mankind.
VI. The other remarkable phenomenon with respect to our union with a material world is, “The dependence of genius, temper, and mental abilities upon the temperature of the body, air, diet, and other such physical causes.” That a variety of mental temperatures, turns, dispositions and abilities prevail among mankind, will not be called into doubt. And as it is certain, that different textures of eyes must see differently; or every object must necessarily partake of the colour with which the eye itself is tainted: so variety in temperature, texture and mould, (so to speak) among minds, must necessarily produce great variety of conceptions, sentiments and judgments, and consequently of inclinations, appetites and dispositions. For, such as the soil is, such will the flavour of the fruit be in the natural world; and by like necessity in the moral, all the impressions, sentiments, judgments, and passions of a mind will be correspondent to its prevailing humour and character: they will necessarily partake in some degree of it. And, hence it is, that every man’s turn of thinking is as distinguishable as his face or gate from that of every other: there are as few minds as faces that have not very peculiar and distinguishing features.a
How far that variety arise from and depends on physical causes.
Now, that differences among minds, in texture and character, abilities and dispositions, are no less necessary to the well-being of society, and variety of beauty and good in it, than differences in complexions and countenances, is very evident at first sight, has been already hinted, and will appear more fully when we come to consider the laws of our nature relative to society. All therefore that belongs to the present question is, how far differences among minds<76> depend upon different textures, and temperaments of bodies, and physical causes, and how and why it is so?
The great extent of this dependence is generally owned.
I. I do not indeed pretend, that there may not be a great variety of genius’s, characters and abilities among pure, unembodied spirits of the same species: on the contrary, wherever there is community, such diversity is absolutely requisite: a moral, as well as a natural whole, must consist of various parts, fitted by their very differences to one another, and to one common end. But it is manifest that the diversity among mankind in genius, temper and abilities, depends, if not totally, yet to a very great degree and extent, upon bodily constitution and mechanical causes. This is so true, that many philosophers have from hence contended, that all is matter and motion; or that we are wholly body. Such an inference is indeed absurd, but the facts from which it is drawn are beyond all dispute; so palpable are they to every one’s feeling and experience. “Each different nation has its national characteristic,a not merely in the features of the face and texture of the body, but likewise in temper and turn of mind.” “Every man is hot or cold, slow or active, phlegmatic or choleric, lively or dull, amorous and delicate, or dull and insensible, correspondently to the temper of his body, his native climate, &c.” “Air and diet change men’s dispositions as much as their bodily habit; a disease, or a blow, do not make a greater alteration in the outward than in the inward man.” Government, civil policy, and religion more especially, have no doubt a very great influence in<77> forming men’s tempers; but, on the other hand, it was never questioned, that the temper of the body, the soil, climate, and many other physical causes have had a very considerable share in originally determining different people into different forms of government, and distinct establishments with regard to civil and religious policy, by their influences upon genius and temper.
It is well worth while to enquire more fully into it.
In fine, it is undeniable, that imagination, memory, and the strength of appetites, very much depend upon bodily habit; and, on the other hand, bodily temperature and habit, depend exceedingly on the exercises of the imagination and appetites; upon the employments, habits, and character of the mind. “Let physicians and anatomists, (says an excellent author)a
