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found the Alani who are tolerant and orthodox Christians, and east of these the Lelgi who are Saracens 361 364 This brings us to the fouthern Shore of the Caspian Sea, where Alexander erected the Ca Spian galeS, as a protection against thein cursion os barbaric tribes frona the north. Rubru quis passed through these gales. This heing the region of Gog and Magog who after rava ging the worid utili hecome at last the mes of Antichrist, it is of the highest importance to the Church that iis geography should be known. The Caspian Sea, eXtending Dom westto east, is as large as the Ponti e Sea, and to compags it is a Murmonilis' journey. Rubruquis traversed itS northern Shore in goingto the Tartar emperor, and itS weStern Shore in re turning. It hasno Connexion with the ocean, being sormed by the Ethilia Volga and other rivers. From the Don to the Ethilia was the land of old calleo Albania, tili latet y occupied by the Cumani. East of the Volga also the Cumanians dweli tili dispossessed by the Tartars. Northward is Asiatic Bulgaria, whose inhabitants are of the sameraCe and language as those on the Danube. East of this region is the land of the Huns . . 364-367 These regions extend as far as Caracathaia or Blach Cathay. Here it is that the emperor of Tartary diuelis, changing his abodeaCCording to the seaSon. It has sonaetimes been Sald that Prester Jolin lived here, but his hingdom, formed of a Nestorian tribe, was far more weSterly. His power was e Stablished on thes death of Coir Cham. Prester John was succeeded by his brother Unc, who took the titie of Cham, and who rei gned for a time in Cara Corum, theprinei pal Tartar City. But Unc Cham Was destro, ed by the Tartarieader Chingliis. His grandson, the son of Unc's daughter, is Mangu Cham to whom Rubruquis was sent by the King of France. Thenanae gi ven to the se Tartars by thenaseives is Moal. They have by this time conquered nearly ali Asia : they hold Russia, Bulgaria, and the ne igh bourhood Os Constantinople ..... 367-371 Eastu ard of BlaCk Cathay are severat tribes with peculiar habiis; and beyond them, to the extreme east, is Great Cathay, the nationof the Seres, whence comes Sillien Clothing. The inhabitants of this Country are Skillat workmen, and acquainted with the medicat propertie S Os planis, and careilly stud y the changes of the pulseand other Sympionis of di Sense. They uSe PRPer-money. They aresor the most part idolaters Buddhist s); but Saracens a re mixed withthem, and alSo Nestorians, who preaCh and practi Se a Corrupi form ofChristiani ty. Their patriarch prosesses Willingness to acknowledgethe aut hori ty of the Roman See. Os these variou S people S Some write from above downwards and from right to test. Others write as wedo, and with our letters. The inhabitants of Eastern Cathay patiat
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det nil ed description 371 376
This geographical description Should be solio ed by an accounturhich I have not beon able to Complete, sa) of the stars, bi of the planeis, scin of the way in whicli the climatic disposition of each placeis assected by them, d) thus malaing true astrological judgement spossibie, e) with the result of promoting the Saset y of the state. Allthat I can do is to offer a se remarkS on these potnis. Each of theii Xed stars has properties of iis o n. Those of the tweive Sigias are Specialty important to us. A Special treati se ivould be needed tode scribe these Characteri Stics adequutely and to poliat out the wayin which ive are affected by them. Each planet has also iis specialcharacter, modi fled by the zodiacat sign in whicli they are siluate, bytheir a specis, that is by any two or more of them being in the Same, in opposite, or in intermediate directionS, by the position reached in their epicycle or occentric, and by the Hoti se of the heavens whichthey may be occupying. This again requires a special treati se . 376 379From this we pass to the effect S produCed by the heavens on places and things upon the emth. The sun may be said to beget no tessthan the parent: and the Stin's influenCe endures through lik. Ea lis pol on the earthys suri age is the Centre M a distinct horigon, and isthus affected differently srom event other. we have to Consider iis distance froni the pole and the equator, what stars are in the Zenith and what signs are dominant there. On ait these potnis the Hebreu nStronomorS are Specialty instructive. Speciat paris of the body are affected by different constellations, and by the position of the moon in them. Each hour of the day is under the controi os a particular planet. On medicat art espe inlly. but also on ali other de pariments of human activi ty, the bearing of AJl this is obviotis. The quartersos the moon must be of course studi ed, and also the dat ly transit of the moon through a portion Of the Zodiae . . . .. 379-385 Hesides the revolutions of the inoon and Sun, attention must begi ven to those of the planeis, especiali y to those of longer period. The Comet sor instance of I 264 was due to Mars, and was related tot he wars in Englanci, Spatia, and Italy of that time. Ali planetaryconjunctionS are important; but of Special importance to man's wellare are the conjunctions of the Moon with stars of VariCuS nature. Position in the orbit must at ways be examine l. in the apSis planetary sorce is grea test: weakest in the opposite potnt. Ce
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must observe too in What hola se each planet may be; sor on this the whole complexion of the year may largely depend. On the regoing data Ne form our judgementS Os evenis paSt, preSent, and future. AS a firSt Step to this xve must forna accurate astronomicaltabies exhibiting the position os the heavenly bodies at any givendate. Comparing these poSitions with the political evenis of sucha date, we obtain methods for irecas ting future evenis. Our bestauthorities on this subjeci are Albumagar, Ptolemy, Haly, and the Hebre in astrologers. A Work of Aristolle on celestiat impres Sion Sshould also be translated 385 390 Next Comes the question, How far Can this knowledge guide otira Clion i We cannot do a way with the force resulting hom any special position of the stars : but we Can modisy our o n action Soas not to be adversely affected by it. Is we know that great Coldi S Coming, we Can malae provision against cold. Similarly the trained astronomer Will provide against peStilen Ce, Or Any other Calami ty which he Sees impencling. Os Such modi*ing influences Moses and Solomon have gi ven examples recorded by JoSephu S. Another instance is the ad vice gi ven by Aristolle to Alexander asto the treat ment of certain perverse tribes : Change their nimOSpherennd thuS Change their morais . 390 394what deters studenis stoin the examination of this subject is sear of the imputation of magi C. Dolabiles s Astrology may be turn ed toa bad account; but So may the most u Seml of tool S. Men do not
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largely assis ted by confidence in their astrologers. Should theymalae Common CauSe with the Saracens, the resulis to Christendommay be disastrous. The Children's Crusade in the last Centvry, and the lascination exerci sed by the Shepherd in otir own time, are proose of what hostile influences may clo is not arrested promptiy. What is needeo is that ait these influences, instead of being COntemptuousty ignored, Should be care sully studi ed, and used under thedirection of the Head of the Church as a defence against the inroad Sof Antichri St .......... 398-403
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In this section there are three paris. The first explaing the generalprincipies of vision. The second deals with direct vision. Thethird with reflected and refracted vi Sion . . . . . l l 66 In Pari I there are twelve DistinCtions. FIRST DISTINCTION, DEALING wITH THE GENERAL CHARACTEROR OPTICA L SCIENCE, AND WITH THE ORGANS OF VISION, PSYCHICAL AND CEREBRA L l l 2CHAPTER I.
The superiori ty of vision to Other senses has been potnted out by Aristolle and other aut hors. Vision reveais the difference of things. It supplies a linodledge of the heavenly hodies. It is the channe los experimental knowledge. Hearing Can give faith, but not prooLof the other Senses we need not speah. Therefore the Sense ofvision becomes the objeCt of a Special SCien Ce . . . . 1 3CHAPTER II.
The fit si thing is to determine the organs of the sensitive Sotai, whicli are to be found in the brain. Others have told us that thevisual nerves issue Dona the bra in ; hut the account gi ven is desective. The brain has two membranes- the Dura Mater, lining the Cranium ;the Pia Mater, ensolding the brain. The bra in has distin Ct Chambers, or celis, ea h of whicli has iis own lanction. In the anterior part of the first celi is sensus communi S. Thi S takeS CogniZance os, and distinguishes, the impressioris brought by eacti Special sense. But itis unable to retain these impreSSions, being loose and stippery. In the bacla part of the fame celi there is the refore the organ ofΙmagination, Whicli, being nei ther too moisi or too dry, Can retain and store up the materiai received by sensus communis. The combi necloperation of these two organ S i S Called PhAntaStia . . . . 4 5
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But animais, though they have not intellect, have other faculti est han those implied in the apprehen Sion of theSe twenty-nine properties. First there is the in Stinet prompting flight Dom an animalos a clangerous specieS, Or approach to one of iis O n, independently of experien Ce. Each object in nature has iis own constitution orcompleXion, and radiates correSponding impressions species) whicli concur with those of like complexion, or disagree with those of unlike. They operate on special and On Common Sen Se, but a re taliencognitance of by a higher faculty of the sensitive foui, which we maycali the estimative sense, and may locate in the posterior celi of thebrain. Eut as in the Case of Sen Sus communis, it does not retain iis impressions, and need S another faculty acting as iis storehouge, thememorative faculty. Midway bet ween these two divisions or celis of the brain is the celi devoted to the cogitative faculty, the mistress faculty in brutes which have not true reason. By this faculty thespicier weaves iis web, the bird iis neSt. In man the rational foui, Coming Dona witho ut, uses this cogitative faculty as iis clites in-
Strument . . . . . . . . . . . . 7 9
That we do not find this vlew of the threesold division os the brain and of animal lacuity in Aristolle is diae to imperfeci translation.
It caia be got frona Avicenna, who has been bet ter translated. AndAvicenna is the greatest philosopher since Aristolle. In any Caseit will not do to conso und the faculty whicli stores sensations with the faculty whicli stores judgemenis, tander the Common name os memory. It must further be stated that while placing these faculties in thebrain, the substance of the brain is not it Sel f sensitive, as Avicennapoinis o ut, re Spect Mily Correcting Aristolle on this potnt. We mustremember however that the Sensitive foui has a twofold organ thebra in and the heart. The lalter is the true seat of ali lii, asAristolle maintains: the former is that whicli first receives impressions and in whicli the variouS Operations of the senses are
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On the origin os the optic nerves. Clearly the lanetion Os visionc annot be undet Stood without a linowledge of the structure of the eye. Most writers on Perspective have ignored this part of the subjeci, or Contented thenaseives with a bare reserenoe to work On medicine. Ι hope ho e ver to malle the matter clear by referen Ce to three aut horities- Atharen, Constantine, and Avicenna. There are two Cavities in the fore part of the brain cal ed ventricles, one On theright, the other on the lest. From these the Opti C nerVCS i Ssue. They meet and Cross ; the right nerve passing to the lest eye, and conversely. In the hollow of the eye the nerve spreads it self out in spherical forna. Each nerve con Sisis of three Coats, the in nermost
derived froni the pia mater; ouisi de this is one coming froin the dura mater; these two are wrapi in a third, coming froni the lining of the si uit 12 i5
arising Dona iis anterior pari. A crystalline or glaciat substance filis the greater part of the Cavity of the eye; it ConSi StS of two paris. The hinder pari, in Contact with the terminat expan Sion of the nerveis like mel ted gla Ss, theiace Called vitreouS ; the anterior pari, whi Chlias received various nam es, is like ice, hall, or Crystal ; it is sonae-what whiter than the vitreous. Anterior to the web, occupying thes pace bet ween ii and the cornea, is the third humour, somewhat like the whi te of egg. On the mode in Whi Ch these paris re Cei Venotarishment there is sonae differen e of opinion. Vision is dependent On the crystalline humour, though not so eSSentialty as on the optic
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The eye approacheS the moSt perfect of geometrical fornas, the Sphere. But bet ween the varioUS humours there are important differe iaces of sorm. The crystalline is a portion os a sphere os different Curvature froin the vitreous. The Centre os curvature Ofthe vitreous is silualed further sorward On the axis of the eye; that of the crystalline further bach ard. The Cornea has the fame Centreas the globe of the eye. The Same may be said of the liquor albugineus. The centre of the livea i S anterior to that of the cornea . . 18-20
it must be remembereo that, in Speaking of these hodies as spherical, we have only to deat with sections of Spheres, relating to those part Sof the eye Concerned with the passage of light. In other paris these Structures are not neceSSarily of Spheri Cal form .... 20 21
The centre of the Consolidativa is generalty placed further bachthan that of the other paris. The truth is that it is not of strictly spherical form, ne i ther is iis inner Suriace Concentri C with the outer. it is of irregular spheroid larua, Some hat prolute On the forward sui face. Hut the Central potnts of ali these ocular structu res ite onone Straight line, as the figure showS 21 25 FOURTH DISTINCTION 26 30
CHAPTER II. The anterior glacialis flens is connected very specialty with the function of vi Sion. It i S mOiSt, for luminous impressions would not
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affect dry sursaces so readi ly ; it is os delicate structure, sui ted tostibile influences of light. It is transparent, yet not too tranSparent, so that the passage of light may leave Suffcient traces to allow of the exerci se of judgement. Iis Suriace formS part Of a larger sphere than that of the vitreous, as ali eady explained 27 28
The vitreous is denser than the Crystalline, so that refraction of the entering ray take S place towarcis the normal. Through it visual impressions are Continued to the expanded fibres of the optic nerve. This nerve is the direct channet os communication with the brain. The consolidativa scierotic) is moist so as to adapt itself to theinward structures ; firm, so as to keep them in their places; and white, So as to Contribute to the beauty of the face . . . 28 29
The eyelids proieci the eyes during fleep, and stom invasion ofirritating particles ; thus the eyes have rest Dorn the toti of receivingimpressions. The lashes moderate the intensi ty Os impression S. Creative goodneSS has supplied two eyes, in CaSe of accident to one ;and to add beauty to the sace. The eyes are Spherical, SO RS to admit of easy and swist motion in ali directions; and algo, hecause had their Suriace been plane, rnys Dona the potnts of a large objectwould not have been normal to the Suriace. AS it is, perpendicularrays impinge upon their sursace hom nearly a Murth part of the horigon ut Once 29 30 FI FTH DISTINCTIOΝ 30 34
We have now explained the instruments of vi Sion. We pass to the function it seis; considering in the firSi place rectilinear Vision. Firsi, we find that impressions must emanate Dona the vi Sible objeCt, a SAristolle has Shown to he the case in every kind of sensation. Visionis a Virtus passiva; but the pasSive must resemble the active, whi hin this case is the visibi e objeci. Thus the species, or impreSSion, is a liken ess of the objeci. These species are thrown out as Doma Centre along every posSibi e radius. Vision then tahes place by the radiation Os species, especialty by thoSe of light and colour. Colour has much to do with vision. A strong Colour impreSSion remain Sin the eye after the object has Ceased to aCt on it. The species oflight are even more essentiat than tho Se os colour . . . 30-32VOL. I. 1
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Uision is not completed in the eye, but in the commissure of the optic nerves with in the brain. Here the impresSions coming stomeach eye Coincide, So that the olaeet is seen as single. I f one of theeyes be forci bly mi Splaced, this coinciden e does not talae place, and the impression os duali ty i S produCed ...... 32 33CHAPTER III.
The terminal potnt of the visual process would seem to be theopti C Commi SSure: in the fame way as the olfactory bulbs terminate the olfactoo process. This in no way conflicts with what has beensa id ag to the location os sensus communis. We are here Speuking oi special sensations. The function of vision then is partialty carri edon within the eye: and is complet ed in the potnt of junction of the
SIXTH DISTINCTION, CONTAINING EXPLANATIONS OF DIFFICULTIES IN THE FUNCTION OF UISION 35-46
CHAPTER I. A difficulty is suggested by the smal iness of the pupil. Although
But independent ly of the cone whose rays fali perpendicularly onthe eye, there is an infinity of others whose rays sali obliquet, . Itwould Seem that Confusion must result. The explanation is that the perpendicular rays Come with much greater forCe, and obscure the effect of the others, as the sun s light conceals the light of the stars. It has further to be observed that of these oblique rays manyare made to Converge by refraction with those whicli fati perpendicularly on the Central part of the eye. There are thus Various degre S in vision. The Central rays and thoSe whicli Converge withthem are Seen Weli: sonae rayS re Sult in imperfeci vision ; sorne innone at ali 37 39