The economy of the animal kingdom, considered anatomically, physically, and philosophically

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AN INTRODUCTI ΟΝ ΤΟ RATIONAL PSYCHOLOGY.

determined by an aura stili more eminent and celestiat, allthings in Whicli are inexpressible, hecause incompreheΠSible, and as it Were continuous, to the inferior sensory n. 623, 624).Τhus as by a Jadder composed of so many Ateps, We in a marinerascend DOm the sphere os visibie effecis or comprehensibie determinationS, to the supreme sphere; and this, according to the maxinis of the old philosophers, Who have asserted, that Superior things do not suffer themsolves to be known, except byreflection, and in effecis, as their mirror. The Chaldaean, Egyptiali, Greeli, and Latin philosophers, were of opinion thatthat there are severat heavens, by Whicli they meant the circumfluent universe. Mercurius Trismegistus, Ρlato, Jamblicus, and Alcinous, belloved thoso heavens to be alive and animaled; and Origen conceived them to have reason, together Mith virtuousand victous inclinations. Aristolle says, indeed, that they areanimaled, but he attributes to them an assistant foui Without intellect; exactly according to Our menning in this theorem. 636. Whence it obtains such a nature, as to be a SubStance

cupabie os formino iis own bo ; a faculty and virtuo Whichliave been trented os in Chapter III. By the nature of a thing, I mean, according to the definition of the philosopher Aristolle ,

iis principio of motion and rest,-a nature in Whicli it is ofitself, and not by iis accidents. According to the Same Ruthor, there are three principies to everything, Vig., matter, Drm, Rud privation, Dom Whicli existes iis nature, so as to be the cause of the things in iis series. The sirst aura is theres oro the matter om Whicli other things are derived; Dom the determination ofiliis aura resulis iis form; to this matter and form may beadded the third principio, or that os privation, to the end thata Substance may exist Whicli subsists by itself, having in it a naturo vhicli is iis principio os motion and rest, in Whieli nature it is of itself, and not by iis accidenis. Thus the sume philosOpher says, that by natural things he means a body resultingsrom the union and composition Os matter und of mr m.

637. And lo have in il lisse, and consequently foui, which is the principie of the thinos elistino in the whole of that series. of this subject wo have troated in Chapter III. Aristolle desines tho soles to be the first perfection Of the natural ogante

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We fir8t live, Dei, ure moved, and understand; but that iis eXtraction is more nobie and exalted. He further affrms, that SOul and form are the first persection of body, and that iis Second are the functions and operations, Whicli depend uponthe first. Theso things are surther troated os in D. 647. 638. Materiality cannot be ascriben to the humati spirituous

matter are assigned iis paris, Whicli are such that quantitycannot be predictited of them, We mean, With the ancientS, Some things in opposition to no things; in Whicli sense, thephilosopher says, that matter is the sirsi subjeci froin Whicli allthings subsist, Whicli are born originalty of them solves, and notthrough the medium of another; and that it is the ultimato pari into Whicli things are resolved, and in Whicli they termi

from the most eminent aura of the worid, and has nothingin it os inertness; because that aura is the most persect forceos nature in a form, and knows nothing either os resiStance,

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others : and thus that one and the fame thing, When nos Similarly conceived as in the succession of things dependent On it,

gives rise to great disagreement, especialty is derived Domihings Whicli are suid to bu included in the principies.

639. Is Wo would explore the essicient, rational, and principat causes of the operations and effecis existing in the animalbody, it Will be necessary sirst to enquire What things, in a Superior degree, correspoud to those Whicli are in an inferior degree, and by What name they are to be callen; Whicli is a

os them. For in proportion as nature ascendS by her degrees,so fhe raises herself Dom the sphere of particular and common expressions to that os universat and eminent ones; till, at tength, in the supreme region of the animal hingdom, Where the humanSOul is, there is no corporeat langunge Whicli can ad equalelyeXpreSS iis nature, and much less the nature of things stili Superior. Where re a mathematical philosophy of universalsmust be invented, Whicli, by characteristic martis and letterS, in their generat form not very unlike the algebrate analysis Ofinii nites, may be capable of expressing those things Whicli are

inexpressibie by ordinary language. Such a philosophy, is Wolldigested, Will be, in a manner, the one science of ali the natural Sciences, hecause it is the complex os all. 640. Besore proceeding to an explication of this part of Our subjeci, it Will be necessary to premise a bries description Ofthe brain und iis substances . For to deduce, a priori, the modein Whicli tho foui 1lows into iis mitid, and the miud intolis body, Would be to aci like an augur Who fhould ulter his predictions bufore he had inspected the eutralis of the victim;

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Other in sige and function, and of Whicli one is called the cerebrum, the other the cerebellum, soW ntid are derived the tWomedullae: the superior of Which having a common connectionWith both tho bruitis, and distinetly deriving iis origin Domeach, is called the medulla oblongata; and tho inferior, vhicli is a continuation Os the superior, is called the medulla vinali8. From the two medullae floW and are derived the nerves, and Domthe nervos ali the texture of the aloinod bo ly. The connectioriand composition of the body ure such, that the body acts and Suffers according to the impulse, and at the plensure, of thebratus; and the connection and composition of the brain are Such, that the brain knows Whatovor is passing in the body, so that everything Whicli occurs in the latior may be under iis regulation, and that everyWhere there may be unanimity and concord in performing the severat offices resulting Dom theseverat divisions os labor. FOr this reason the superior medulla, as to a great part of it, appears to he a continuation, appendix, and ost Spring of the braitis; the inferior medulla tobe a continuation, appendix, and Ompring of the superior; thenerVOS, to be a continuation, appendix, and ost spring of the medullae; and the body to be a continuation, appendiX, and Omspring of the nerVOS. 642. Each brain and each medulla is oncompassed With iis

Conis and membranes, Whicli are callest matres and meninge8. That Which soritis the outermost furtace, and lines the inside of the situli, is the dura mater, or crassa meninoe; that Whicli Occupies the place nexi to the brains, is the pia mater, or tenui8meninae. A nother covering also intervenes, Os a reticular form,

called the arachnoid, Whicli, like a lymphatic duci projected into a plane, incloses the better lymph, Or nervous juice, and dispenses and distributes it tuto the beginnings of the nerves,

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the provinces of tho body, and descend into iis hollows and vul-leys, they gradually lay their conis aside again. The Derves them Selves, With their membranes, become finer anil siner in their progress, tili they attain their extremities and the inmost paris of the Viscera, Where at tength they are possessed of Such udelicacy, form, face, and expansion, that they are assected by the stightest modes, changes, and disserences, anSWering to Similar ones in the braitis to Whicli they retiarn. Thus the brain, in iis sirst principie, is made sensibie of Whateuer is transaeting in ali tho extremities of iis Lingdom. 643. Each brain and encli medulla consisis principalty of

three substances; the first of Whicli, When Occiapying the OUter-most region of the brains, is called the cortical substance, and When occupying the inner region, as in the medullae, is called the cineritious substance. The second is called the medullary Orwhile substance, and is alWays in continuity With the cortical orcineritious. The third is producen Dom the minute arteries, Whicli, accompanying the meniuX, penetrate into the brain, and uufolii thomselves everyWhere in iis minute SpaeeS. 644. The cortical substance, either Wheu lying proximatelybeneath the pia mater, and Watered, nourished, and cherished by the purer blood, or When, under the nume of the cineritious substanee, it OecupieS Various tracis more remote DOm the

heis of glasses, be seen to consist entirely Os minute spherialesnearly approaching to an ovat form. The cerebrum and cere- bellum themselves, ulso approach nearly to the spherical and Ovallarm, and thus assume a Shape like that os their paris. Helice these minute organic Substances, inasmuch as they are liketheir Whole, and have the Same potency individually, Whicli, conjointly and aggregately, is exerciSed in the compotand, meritthe name of cerebellum. The eye also, by artificiat aid, is en- abled to discover that these forins, spherules, Or Cerebellula, Rreclothed With, and inclosed iti, a membrane or meninX, mueli in the fame muniter as the brain iiself, excepi that their membraneor meninx deserves the titie of pia in the superlative degree, and that thoy aro distinguished horti their neighboring and aSSO-ciate spheriales of the samo Lind. It may ulso bo discerned, that these most delicate conis are composed os villi und capillary

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ShOOtS, Os most minute arteries, in multitude innumerabie, in determination Wonderfui, and in ordor most bestiati sui; Whicli diffuse in ali directions a volatile and spirituous fluid, educednom the blood, and conceived by eminent generation in theirmOSi pure WOmbs. These cerebellula appear to be the internat SenSOries, Whicli receive impressions and modifications Dom theeXternat sensortes, and Whicli convey them asterWards higher usto the judgment-sent of the mind. These cerebellula beingagain collectod into tori or masses of different forms, and en- compassed by a complication of minute Vesseis, construet and constituto a Lind of second dimenSion Os organie partS. 645. When, there re, animal nature, in this last aridsirst end of iis arteries, nerves, and tuuies, has sirsi moulded iis Organte elements into spheres of the most perfeci forna, so that

ever is passing With in the range of iis appendages; it nexibeeomeS necessa , in order sor it to contemplato the state of iis economy in and Dom these organio elemenis, to emit radii into the Wholo circumferetice of iis dominion; it there re puis forthminute fibriis Dom each of these conglomerat ed spheriales, bymeans of Whicli it continues itself to ali the ultimates of iis Lingilom; much in the fame manner as the brain, Whicli is the complex os ali the spherules, continues itSelf, On a larger Scale, into iis medulla oblongata and medulla spinalis, and thetice into the nerves. Those cineritious particles clotho the fibriis emitted DOm themselves, With conis, in an Ordor similar to that in Whichthe brain at largo clothes iis medullae and emiSSary nerVOS. Henee, Whatever os a fibrillary nature is visibie in the medulla Or White Substance, is derived Dom tho cortical and cineritious SubStanee, as iis parent. M any of these minute fibriis collected into a fasciolo, and clothed in like manner With a membrano, Originate a second dimension os fibrii, corresponding ton collection Of the samo number os cortical spherules. In the Same manΠer is originated also a third dimension euvelopedWith tunius; to Whicli auswers tho brain iiself, Whicli, Withthese, proceeds through the foramen magnum of the Occiput into the cavi ty formed by the vertebrae, doWn to the OS Sacrum and Os coccygis; and Whicli Dom this cavlty, through the Verte' brat holes and notches, proceeds Onward, to excite and Strengthen

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Inasmuch as the arteries of the brain continuatly dividothemselves, untii they become most minute capillary tubes and stamenis, and are continued into ali the cortical substance; thecortical and cineritious substances depend Dom the shoois Oftheir minute arteries, like mulberries and olderberries from thetender stallis of their boughs, or like clusters Dom the branchos Of the vine, Or else like Other forms according to the disserent Species of the animais, so that they seem to be similar to the ultimate essecis in stirubs, and to resemble, as it Were, the litile Seeds, in Whicli the most preci ous juice, issuing Dom a richVein, terminates and concentrates isseis; just as in citron audother precious fruit-trees, in Whicli one citron or Other fruit perpetuatly comes to iis birili as another drops of , that it mayalWays have something Dom Which to begin anes, and in Whichio enelose and transmit iis allisthesi and most hight y resinedeSSence ; and also that it may represent most purely What is the

Τhe bratu has, in general, tWo ossices to persorm : the fir8t,to Will What it knows, and to know What it Wilis; the second, to transmit in to the blood, contained in the sinuses at iis base, a certain most nobie fluid, elaboraten in iis cortical spherules. To tho sirst kind of theso ossices are appotnted ali the organicsariS Which encompass and constituto tho sursace like a corteX

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lectuat organs : they ure moreover so separated by an interVCH-ing Septum Or lance, that one cannot enter into the province Ofthe other, excepi by a most generat mode of acting. Is hoWever We u Ouid see hoW, by a most Wonderfui contriv-ance, ait things are arrangod in their respective Order, Wemust Conceive of the whole brain us formon in motion and formotion, or represent it to Oursei vos as having an animation; that is, an alternate expansion and contraction. For thus Weshali see What is the function, cause, and mode of Reting, Proserto each pari: since the individunt paris are so arrvnged in reser ence to eueli Other, under the more generat, and theSe under

the most generat, that Whilst the whole draWs iis breuth, thereis no part but is draWing iis breatli ut the fame time, Or contributing to the animation of the whole; for Which reason, ure have been led to say, that ali the paris of the brain are siluated in

the strenui Os iis motion n. 219, 258, 28 I, 287, 557).

Tho bruin is constructed With a vieW to reciprocate the alternations of iis animation in so Orderly a manner, that ussienever it spirates and respirates, it refers itself hom iis sursaces to iis planes, Dom iis planes to iis axes, and Dom iis axes to iis centres. For iis Surfaces are severat. Iis Outermost is constituted by the dura mater Or crassa meninx; the nexi by the thin membrane called the pia mater; and the nexi by the membrane culled the arachnoid. Under this three id sursace is deposited the cortical substance; Which bcing the part that encompasSes the centrum Ovale Or medullary nucleus, discli arges RS asori os cortex the Ossice of n Sursaee.

The Common or generat planes are those Whicli are called the processes. One of these divides the cerebrum into tWo hemisphores : it is called the sirst, the vertical, the longitudinal, and the faci rin process, or falx: proceeding Dona the crista galli,

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proce8s of the dura mater, Whicli is continuod nostr . the laurili sinus Dom the superior process, descend s to the cerebrum be- tWeen ii and the cerebellum, and proceeds sideWays, in each direction, to the opposite regions of the cranium. It thus involves the cerebrum, and divides it Dom the cerebellum, so that both may discliarge their ossices conjointly and Separalely. There are also tWo axes. One of these, Whicli is the transverse, descends DOm the highest region of the cranium, Where the cannis of the sinu ses meet in the oecipital bone above thecerebellum, and passes mid Way betWeen the cerebrum and the cerebellum, doWn to the isthmus of the ancients, or the regionos the pineat gland, the nates, and testes. This axis is constitutud by the laurili sinus iiself, or the torcular Herophili, andis supported by the isthmus. The sinus seems to terminate iuthe third ventriolo; for it is thero talion up by a vein Whicli is Sometimes double, and ruris across the ventricte: but vhen itdescends there tuto the chemicat laboratory, it is immediatelycontinued Dom the infundibulum into the pituitary gland; a gland whicli thus occupies the other extremity of this axis. The second, or the longitudinat axis, begitis in the crista et i- moides, Where it is divided; but is continued, through the olestos the septum lucidum, under the sornix, across the third ventricle and the aqueduet, and so through the laurili ventricle and the calamus scriptorius, tili it reaches beyond into the spina dorsi. It malles iis appenrance On Separating the hemispheres and tining Out the corpus callosum; and iis continued progression is seen On ruising up the isthmus and the cerebellum. Itis thus a common or generat canal, Surrounded and shut in onevery fide Mith batilis, Which have here and there intervening

The centres are formed by the pineat gland and tho buse of

the fornix, placed ut the two extremities of the third ventricie. There are tWO of them, because, as Observed ab ove, the brain has tWo generat ossices. One of these centres, Or the base of the fornix, acts as a peduncte to the Chemicat laboratory, to collect and transmit iis medullary substanee; Whenee, in a certatu sense, it may be called the centre os rest, the other being the

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divided part of tho brain; as in ali that whicli constitutes iis

CorteX, and is composed os conglomeraten cortical Substances; lar every conglomeration has respeet, Dom itS proper Sursaee, to iis planes, Dom iis planos to iis axes, and Dom iis axes to iis sed lancles, as to iis centres; much as is the case With the bratuin generat. Even the pia mater, Whicli iS the common Sursace, everyWhere insinuates and ensolds itself among the serpentineanfractuosities, much as the falx does betWeen the hemispheres; by Whicli means there are insinuated as many planes as thereare congeries formed os sueti Substances. Along these planesthere also everyWhere descend arteriai sinuli, just as tho murthsinus descends belWeen the cerebrum and cerebellum; and these, by their descent, form a species of axes. These arteriai Sinuli, Soon running Out into ramificati Ons, at tengili determine themselves into the individual cortical spherules, as into somany centres; DOm Whicli are educed fibriis compacted intopeduncles, Whicli then enter the medullary globe. But it is not so easy to discover What representation of the processes and centros is exhibited in the sursace itself of these congeries Or tori os the cortical substance, excepi by comparing them Withthe cerebellum, Whieli is the greatest cortical congeries Or torus,

and an effigy of Whicli, in miniaturo, is assorded by these of thebrain; for When they aro dissected and examinod as to their in-most Structure, We find a situdo ving sorti, of the fame arborealramification as in the cerebellum. NoW as the above mentioned cortical tori are most regularly formed in motion and sor motion; so also are the individunt cortical spherules, Whieli are composed os vesseis divaricated in to the most delicate fibres: and as they are most perfeci formSand organic paris, it may be inserrod Without doubi, Dom theregularit ' of the paris compotin ded of them, that they also havea most distinui relation, froin their piissimae matres to their planes, from their planes to thoir axes, and from these to their CentreS. For they are so mutuatly discriminated one frum theother, and SO perpetuatly conjoined, as to be enabled to actas the beginnings of determinations. For One Spherule, bygenerat and particular contudi and connection, has reSpeet tonnother RS the companion of iis fasti : so also have the fibres