504 



NA TURE 



\Oct. 17, 1872 



sponding somewhat to our .tttraction and repulsion. lie en- 

 deavoured to prove the four-clomenl tlieory by the following crude 

 experiment : woDd is burnt upon a hearth, fire seems to be 

 evolved from it, the smoke is air, moisture is deposited on tlie 

 hearthstone, wliile the ashes are earth, hence wood is made up 

 of earth, air, fire, and water. Empedoliles was one of the first 

 to materialise the Homeric gods ; he applied his four-element 

 theory even to them, declaring: that Zeus was tlie element of fire, 

 Here tlie element of air, Nestis the element of water, and Aido- 

 neus the element of earth. Ilcralileitos (about 460 B.C.) made 

 fire the primal element, and assumed tliat it condensed itself into 

 the material elements, and that air, water, and earth were respec- 

 tively formed as the fire became more condensed. He asserted, 

 moreover, that all things are in perpetual motion and change, the 

 moving force being fire ; "fire is to him," says .Schwegler, "even 

 in individual things, the principle of movement, of physical as of 

 spiritual vitality ; the soul itself is a fiery vapour." We find in 

 the fire of Herakleitos to some extent the attributes of what we 

 now call a physical force ; thus it is precedent to matter, and is 

 the motive power of the universe, it influences and changes matter, 

 it is perpetually undergoing transformation, but ultimately returns 

 to its own form. Prof. Max Midler speaks of Herakleitos as 

 "one of the boldest thinkers of ancient Greece." We can well 

 understand why fire should, at a very early date, be regarded as 

 chief of the elements, and the motive power of the universe ; it 

 h.ad long been worshipped as a symbol of the deity by the Clial- 

 dixiins ; a worship which possibly originated with the Scytlis ; 

 for Zoroaster, who introduced fire worsliip among the Medo- 

 Persic races, is supposed to have been a Scythian. Again, Agni, 

 the god of light and fire, was placed first in the Hindu Trinity. 



Anaxagoras of Klazomene (li.C. 500) asserted that originally 

 all things existed in infinite disorder ; before the creation there 

 was a chaos of mingled particles of matter, which were arranged 

 in order by a designing intelligence or mover of matter (fuiJO. 

 The primitive constituents of things are not definite elements, 

 like those of Empcdokles, but are hoimvivneiics {dp.oioix4peiai) 

 that is like parts, small particles of matter like the masses they 

 produce when they aggregate. Thus a mass of iron is produced 

 by the aggregation of an infinite number of iron-liomceomsries 

 briiught out of the chaos by the vaus, which latter possesses 

 vortical motion which enables it to separate like parts and bring 

 them together, somewhat on the principle of gold-washing. If 

 a dish containing substances of different relative weight, such as 

 cork, sand, and lead shot, intimately mixed together, be caused 

 to rotate, like particles will come together, the lead in one place 

 the sand in another, and this experiment will help us to realise 

 to some extent the meaning of Anaxagoras when he assumes that 

 the vortical motion of the vom caused homceomeries to aggregate 

 anl form the world. Leukippos taught that the world is pro- 

 duced by the falling together of small indivisible particles or 

 aloins (from a and Tf/ii'oi), which are the principles of things, 

 and which possess rapid circular motion. Deoiokritos (460 B.C. ) 

 extended the atomic theory of Leukippos ; he contended that 

 the principles of things are atoms and a vacuum. The atoms are 

 invisible by reason of their smallnes.s, indivisible by reason of 

 their solidity, impenetrable and unalterable. They have no other 

 qualities, neither heat, nor cold, nor colour. Atoms are infinite 

 in number, the vacuum is infinite in magnitude. Atoais differ 

 from each other in size, shape, and weight. They are actuated 

 by necessity or fate {a.vaxKr\\ and possess an oblique motion in 

 the vacuum, which causes atoms of like shape to collide and 

 group themselves together, by which means all things are formed. 

 The vacuum is necessary, otherwise motion of the atoms would be 

 impossible, because there would be no place to receive tliem. Long 

 before the time of Demokritos an atomic theory had been proposed 

 inlndiabyKanada, thefounder of the Nyaya system of philosophy, 

 of which this theory forms the distinguishing feature. The theory 

 of Leukippos is attributed by Possidonius to Moschus, a Phce- 

 nician. Daring the Middle j\ges many writers made the atomic 

 theory a prominent part of their system. Descartes adopted it 

 in a somewhat modified form, and associated with his particles 

 the vortical motion possessed by the homoeomeries of Anaxagoras. 

 Finally, almost in our own day, the atomic theory was introiluccd 

 into chemistry by Dalton, and its introduction marked an im- 

 portant era in the science. At the present time the doctrine of 

 atoms forms a principal feature in chemistry, and other 

 branches of science find the conception most conducive to the 

 philosophical explanation of phenomena. The definition of an 

 atom given by Demokritos is almost as absolute and precise as 

 that which we find in our most modern treatises. Thus the theory 



has endured for more than twenty-five centuries, and is likely to 

 endure until there shall be no more science. It offers a striking 

 example of the oneness of physical thought ; the conception 

 seems to be essential to Natural Philosophy ; the most stupjn Ions 

 phenomena may be referred to atomic motions. S. Augustine 

 has well said, "Deus est magnus in magnis, maximus autem in 

 minimis." 



The Hindus not only possessed the idea of the atomic consti- 

 tution of matter, but further associated an attractive force with 

 the atoms. This is well shown in the following extract given by 

 Sir William Jones, from the poem of " Shi'ri'n and Ferh.ad, or the 

 Divine Spirit, and a human soul disinterestedly pious" : —"There 

 is a strong propensity, which dances through every atom, and 

 attracts the minutest particle to some peculiar object ; search this 

 Universe from its base to its summit, from fire to air, from water 

 to earth, from all below the moon to all above the celestial 

 spheres, and thou wilt not find a corpuscle destitute of that 

 natural attractibility ; the very point of the first thread in this 

 apparently tangled skein ; is no other than such a principle of 

 attraction, and all principles beside are void of a real basis ; from 

 such a propensity arises every motion perceived in heavenly or in 

 terrestrial bodies ; it is a disposition to be attracted, which taught 

 hard steel to rush from its place and rivet itself on the magnet ; 

 it is the same disposition which impels the light straw to attach 

 itself firmly to the amber ; it is this quality which gives every 

 substance in nature a tendency towards another, and an inclina- 

 tion forcibly directed to a determinate point." 



The most prolific writer on Science amongst the ancients was 

 Aristotle {b. 3S5 B.C., d. 322). He was the author of various 

 treatises, on the Heavens, on Generation and Corruption, on 

 Physics, on Respiration, on Audibles, &c., and his views as well 

 on metaphysics and ethics, as on science, were nearly universally 

 accepted during the Middle Ages. Indeed, the scientific writings 

 of Aristotle influenced science for nearly twenty centuries. Few, 

 however, of his opinions concern us here. He was the first to 

 introduce into Greek philosophy the t'//;t'/', which he regarded as 

 a fifthelement (hence afterwards called quinta essentia) more subtle 

 and divine than the other elements. The word quintessence is 

 frequently used by the alchemists and early chemists, and is found 

 in our most recent English dictionaries. The idea of an infinitely 

 rarified and all-penetrating matter had long existed in physical 

 philosophy, notably in the Hindu systems ; it was probably recog- 

 nised as a fifth element prior to the ninth century B.C. Aristotle 

 IS said to have called it aiOijp from ciei and flew, because he con- 

 ceived it to be always in motion, and to be the moving agency of 

 the other elements ; but we cannot admit this derivation now, and 

 prefer to trace it to aWtn and iiidh. In the present day we find it 

 impossible to explain various phenomena, notably those connected 

 with radiant heat and the polarisation of light, without assuming 

 the existence of some rare ethereal medium, cubic miles of which 

 would not weigh a milligramme, and we still call it the ether. Few 

 physical systems have avoided tins supposition ; we make less use 

 of it in chemistry than in physics ; but it would be difficult to 

 account for such aclioiis as the combination of chlorine and hy- 

 drogen under the influence of light, without it. Aristotle held 

 that the four elements are mutually convertible, and he assigned 

 two qualities to each, one of which was common to some other 

 element. Thus lie said : — 



I'"ire is hot and dry. 



Air is hot and moist. 



Water is cold and moist. 



Earth is cold and dry. 



In each of these one quality is dominant. Thus fire is more 

 hot than dry, air more moist than hot, water more cold than 

 moist, and earth more dry than cold. If the dry of fire be 

 vanquished by the moist of water^ air will result ; if the hot of 

 air be vanquished by the cold of earth, water will result ; if the 

 moist of water be vanquished by the dry of fire, earth will result. 

 This idea of the transmutation of the elements was adopted 

 generally in works on alchemy ; the following figure which em- 

 bodies it is from a work entitled "Preciosa Margarita Novella," 

 published in Venice in 1546. 



Aristotle's metlio.i of expressing the transmutation of the ele- 

 ments does not seem to differ much from that of earlier philo- 

 sophers ; it would a|>pear that he means to imply that if water 

 be heated air is produced, while if it be heated more strongly so 

 as to evaporate it to dryness, earth is left. His account of the 

 generation of fire from air and earth is based on the most shallow 

 and meagre observation, and shows to what results the most 



