Cicero's Tusculan Disputations / Also, Treatises On The Nature Of The Gods, And On The Commonwealth

by Marcus Tullius Cicero

Human art and industry are indeed necessary towards the preservation and improvement of certain animals and vegetables; for there are several of both kinds which would perish without that assistance. There are likewise innumerable facilities (being different in different places) supplied to man to aid him in his civilization, and in procuring abundantly what he requires. The Nile waters Egypt, and after having overflowed and covered it the whole summer, it retires, and leaves the fields softened and manured for the reception of seed. The Euphrates fertilizes Mesopotamia, into which, as we may say, it carries yearly new fields.[²²⁸] The Indus, which is the largest of all rivers,[²²⁹] not only improves and cultivates the ground, 306but sows it also; for it is said to carry with it a great quantity of grain. I could mention many other countries remarkable for something singular, and many fields, which are, in their own natures, exceedingly fertile.

LIII. But how bountiful is nature that has provided for us such an abundance of various and delicious food; and this varying with the different seasons, so that we may be constantly pleased with change, and satisfied with abundance! How seasonable and useful to man, to beasts, and even to vegetables, are the Etesian winds[²³⁰] she has bestowed, which moderate intemperate heat, and render navigation more sure and speedy! Many things must be omitted on a subject so copious—and still a great deal must be said—for it is impossible to relate the great utility of rivers, the flux and reflux of the sea, the mountains clothed with grass and trees, the salt-pits remote from the sea-coasts, the earth replete with salutary medicines, or, in short, the innumerable designs of nature necessary for sustenance and the enjoyment of life. We must not forget the vicissitudes of day and night, ordained for the health of animated beings, giving them a time to labor and a time to rest. Thus, if we every way examine the universe, it is apparent, from the greatest reason, that the whole is admirably governed by a divine providence for the safety and preservation of all beings.

If it should be asked for whose sake this mighty fabric was raised, shall we say for trees and other vegetables, which, though destitute of sense, are supported by nature? That would be absurd. Is it for beasts? Nothing can be less probable than that the Gods should have taken such pains for beings void of speech and understanding. For whom, then, will any one presume to say that the world was made? Undoubtedly for reasonable beings; these are the Gods and men, who are certainly the most perfect of all beings, as nothing is equal to reason. It is therefore credible that the universe, and all things in it, were made for the Gods and for men.

But we may yet more easily comprehend that the Gods have taken great care of the interests and welfare of men, 307if we examine thoroughly into the structure of the body, and the form and perfection of human nature. There are three things absolutely necessary for the support of life—to eat, to drink, and to breathe. For these operations the mouth is most aptly framed, which, by the assistance of the nostrils, draws in the more air.

LIV. The teeth are there placed to divide and grind the food.[²³¹] The fore-teeth, being sharp and opposite to each other, cut it asunder, and the hind-teeth (called the grinders) chew it, in which office the tongue seems to assist. At the root of the tongue is the gullet, which receives whatever is swallowed: it touches the tonsils on each side, and terminates at the interior extremity of the palate. When, by the motions of the tongue, the food is forced into this passage, it descends, and those parts of the gullet which are below it are dilated, and those above are contracted. There is another passage, called by physicians the rough artery,[²³²] which reaches to the lungs, for the entrance and return of the air we breathe; and as its orifice is joined to the roots of the tongue a little above the part to which the gullet is annexed, it is furnished with a sort of coverlid,[²³³] lest, by the accidental falling of any food into it, the respiration should be stopped.

As the stomach, which is beneath the gullet, receives the meat and drink, so the lungs and the heart draw in the air from without. The stomach is wonderfully composed, consisting almost wholly of nerves; it abounds with membranes and fibres, and detains what it receives, whether solid or liquid, till it is altered and digested. It sometimes contracts, sometimes dilates. It blends and mixes the food together, so that it is easily concocted and digested by its force of heat, and by the animal spirits is distributed into the other parts of the body.

LV. As to the lungs, they are of a soft and spongy substance, which renders them the most commodious for respiration; 308they alternately dilate and contract to receive and return the air, that what is the chief animal sustenance may be always fresh. The juice,[²³⁴] by which we are nourished, being separated from the rest of the food, passes the stomach and intestines to the liver, through open and direct passages, which lead from the mesentery to the gates of the liver (for so they call those vessels at the entrance of it). There are other passages from thence, through which the food has its course when it has passed the liver. When the bile, and those humors which proceed from the kidneys, are separated from the food, the remaining part turns to blood, and flows to those vessels at the entrance of the liver to which all the passages adjoin. The chyle, being conveyed from this place through them into the vessel called the hollow vein, is mixed together, and, being already digested and distilled, passes into the heart; and from the heart it is communicated through a great number of veins to every part of the body.

It is not difficult to describe how the gross remains are detruded by the motion of the intestines, which contract and dilate; but that must be declined, as too indelicate for discourse. Let us rather explain that other wonder of nature, the air, which is drawn into the lungs, receives heat both by that already in and by the coagitation of the lungs; one part is turned back by respiration, and the other is received into a place called the ventricle of the heart.[²³⁵] There is another ventricle like it annexed to the heart, into which the blood flows from the liver through the hollow vein. Thus by one ventricle the blood is diffused to the extremities through the veins, and by the other the breath is communicated through the arteries; and there are such numbers of both dispersed through the whole body that they manifest a divine art.

Why need I speak of the bones, those supports of the body, whose joints are so wonderfully contrived for stability, and to render the limbs complete with regard to motion and to every action of the body? Or need I mention 309the nerves, by which the limbs are governed—their many interweavings, and their proceeding from the heart,[²³⁶] from whence, like the veins and arteries, they have their origin, and are distributed through the whole corporeal frame?

LVI. To this skill of nature, and this care of providence, so diligent and so ingenious, many reflections may be added, which show what valuable things the Deity has bestowed on man. He has made us of a stature tall and upright, in order that we might behold the heavens, and so arrive at the knowledge of the Gods; for men are not simply to dwell here as inhabitants of the earth, but to be, as it were, spectators of the heavens and the stars, which is a privilege not granted to any other kind of animated beings. The senses, which are the interpreters and messengers of things, are placed in the head, as in a tower, and wonderfully situated for their proper uses; for the eyes, being in the highest part, have the office of sentinels, in discovering to us objects; and the ears are conveniently placed in a high part of the person, being appointed to receive sound, which naturally ascends. The nostrils have the like situation, because all scent likewise ascends; and they have, with great reason, a near vicinity to the mouth, because they assist us in judging of meat and drink. The taste, which is to distinguish the quality of what we take; is in that part of the mouth where nature has laid open a passage for what we eat and drink. But the touch is equally diffused through the whole body, that we may not receive any blows, or the too rigid attacks of cold and heat, without feeling them. And as in building the architect averts from the eyes and nose of the master those things which must necessarily be offensive, so has nature removed far from our senses what is of the same kind in the human body.