6。Butsuchcitiesaslietothewest，andwhichareshelteredfromwindsblowingfromtheeast，andwhichthehotwindsandthecoldwindsofthenorthscarcelytouch，mustnecessarilybeinaveryunhealthysituation:inthefirstplacethewatersarenotclear，thecauseofwhichis，becausethemistprevailscommonlyinthemorning，anditismixedupwiththewateranddestroysitsclearness，forthesundoesnotshineuponthewateruntilhebeconsiderablyraisedabovethehorizon。Andinsummer，coldbreezesfromtheeastblowanddewsfall；andinthelatterpartofthedaythesettingsunparticularlyscorchestheinhabitants，andthereforetheyarepaleandenfeebled，andarepartlysubjecttoalltheaforesaiddiseases，butnooneispeculiartothem。Theirvoicesareroughandhoarseowingtothestateoftheair，whichinsuchasituationisgenerallyimpureandunwholesome，fortheyhavenotthenorthernwindstopurifyit；andthesewindstheyhaveareofaveryhumidcharacter，suchbeingthenatureoftheeveningbreezes。Suchasituationofacitybearsagreatresemblancetoautumnasregardsthechangesoftheday，inasmuchasthedifferencebetweenmorningandeveningisgreat。Soitiswithregardtothewindsthatareconducivetohealth，orthecontrary。
　　7。AndIwishtogiveanaccountoftheotherkindsofwaters，namely，ofsuchasarewholesomeandsuchasareunwholesome，andwhatbadandwhatgoodeffectsmaybederivedfromwater；forwatercontributesmuchtowardshealth。Suchwatersthenasaremarshy，stagnant，andbelongtolakes，arenecessarilyhotinsummer，thick，andhaveastrongsmell，sincetheyhavenocurrent；butbeingconstantlysuppliedbyrain-water，andthesunheatingthem，theynecessarilywanttheirpropercolor，areunwholesomeandformbile；inwinter，theybecomecongealed，cold，andmuddywiththesnowandice，sothattheyaremostapttoengenderphlegm，andbringonhoarseness；thosewhodrinkthemhavelargeandobstructedspleens，theirbelliesarehard，emaciated，andhot；andtheirshoulders，collar-bones，andfacesareemaciated；fortheirfleshismelteddownandtakenupbythespleen，andhencetheyareslender；suchpersonsthenarevoraciousandthirsty；theirbelliesareverydrybothaboveandbelow，sothattheyrequirethestrongestmedicines。
　　Thisdiseaseishabitualtothembothinsummerandinwinter，andinadditiontheyareverysubjecttodropsiesofamostfatalcharacter；andinsummerdysenteries，diarrheas，andprotractedquartanfeversfrequentlyseizethem，andthesediseaseswhenprolongeddisposesuchconstitutionstodropsies，andthusprovefatal。Thesearethediseaseswhichattacktheminsummer；butinwinteryoungerpersonsareliabletopneumonia，andmaniacalaffections；andolderpersonstoardentfevers，fromhardnessofthebelly。Womenaresubjecttooedemaandleucophlegmasiae；whenpregnanttheyhavedifficultdeliveries；theirinfantsarelargeandswelled，andthenduringnursingtheybecomewastedandsickly，andthelochialdischargeafterparturitiondoesnotproceedproperlywiththewomen。Thechildrenareparticularlysubjecttohernia，andadultstovaricesandulcersontheirlegs，sothatpersonswithsuchconstitutionscannotbelong-lived，butbeforetheusualperiodtheyfallintoastateofprematureoldage。Andfurther，thewomenappeartobewithchild，andwhenthetimeofparturitionarrives，thefulnessofthebellydisappears，andthishappensfromdropsyoftheuterus。SuchwatersthenIreckonbadforeverypurpose。Thenexttotheminbadnessarethosewhichhavetheirfountainsinrocks，sothattheymustnecessarilybehard，orcomefromasoilwhichproducesthermalwaters，suchasthosehavingiron，copper，silver，gold，sulphur，alum，bitumen，ornitre（soda）inthem；foralltheseareformedbytheforceofheat。Goodwaterscannotproceedfromsuchasoil，butthosethatarehardandofaheatingnature，difficulttopassbyurine，andofdifficultevacuationbythebowels。Thebestarethosewhichflowfromelevatedgrounds，andhillsofearth；thesearesweet，clear，andcanbearalittlewine；theyarehotinsummerandcoldinwinter，forsuchnecessarilymustbethewatersfromdeepwells。Butthosearemosttobecommendedwhichruntotherisingofthesun，andespeciallytothesummersun；forsucharenecessarilymoreclear，fragrant，andlight。Butallsuchasaresalty，crude，andharsh，arenotgoodfordrink。Buttherearecertainconstitutionsanddiseaseswithwhichsuchwatersagreewhendrunk，asIwillexplainpresently。Theircharactersareasfollows:thebestaresuchashavetheirfountainstotheeast；thenext，thosebetweenthesummerrisingsandsettingsofthesun，andespeciallythosetotherisings；andthird，thosebetweenthesummerandwintersettings；
　　buttheworstarethosetothesouth，andthepartsbetweenthewinterrisingandsetting，andthosetothesouthareverybad，butthosetothenortharebetter。Theyaretobeusedasfollows:whoeverisingoodhealthandstrengthneednotmind，butmayalwaysdrinkwhateverisathand。Butwhoeverwishestodrinkthemostsuitableforanydisease，mayaccomplishhispurposebyattendingtothefollowingdirections:Topersonswhosebelliesarehardandeasilyburntup，thesweetest，thelightest，andthemostlimpidwaterswillbeproper；butthosepersonswhosebelliesaresoft，loose，andpituitous，shouldchoosethehardest，thosekindsthataremostcrude，andthesaltiest，forthuswilltheybemostreadilydriedup；forsuchwatersasareadaptedforboiling，andareofaverysolventnature，naturallyloosenreadilyandmeltdownthebowels；butsuchasareintractable，hard，andbynomeansproperforboiling，theseratherbindanddryupthebowels。Peoplehavedeceivedthemselveswithregardtosaltwaters，frominexperience，fortheythinkthesewaterspurgative，whereastheyaretheveryreverse；forsuchwatersarecrude，andilladaptedforboiling，sothatthebellyismorelikelytobeboundupthanloosenedbythem。Andthusitiswithregardtothewatersofsprings。
　　8。Iwillnowtellhowitiswithrespecttorain-water，andwaterfromsnow。Rainwaters，then，arethelightest，thesweetest，thethinnest，andtheclearest；fororiginallythesunraisesandattractsthethinnestandlightestpartofthewater，asisobviousfromthenatureofsalts；forthesaltishpartisleftbehindowingtoitsthicknessandweight，andformssalts；butthesunattractsthethinnestpart，owingtoitslightness，andheabstractsthisnotonlyfromthelakes，butalsofromthesea，andfromallthingswhichcontainhumidity，andthereishumidityineverything；andfrommanhimselfthesundrawsoffthethinnestandlightestpartofthejuices。Asastrongproofofthis，whenamanwalksinthesun，orsitsdownhavingagarmenton，whateverpartsofthebodythesunshinesupondonotsweat，forthesuncarriesoffwhateversweatmakesitsappearance；butthosepartswhicharecoveredbythegarment，oranythingelse，sweat，fortheparticlesofsweataredrawnandforcedoutbythesun，andarepreservedbythecoversoasnottobedissipatedbythesun；butwhenthepersoncomesintotheshadethewholebodyequallyperspires，becausethesunnolongershinesuponit。Wherefore，ofallkindsofwater，thesespoilthesoonest；andrainwaterhasabadspotsmell，becauseitsparticlesarecollectedandmixedtogetherfrommostobjects，soastospoilthesoonest。
　　Andinadditiontothis，whenattractedandraisedup，beingcarriedaboutandmixedwiththeair，whateverpartofitisturbidanddarkishisseparatedandremovedfromtheother，andbecomescloudandmist，butthemostattenuatedandlightestpartisleft，andbecomessweet，beingheatedandconcoctedbythesun，forallotherthingswhenconcoctedbecomesweet。Whiledissipatedthenandnotinastateofconsistenceitiscarriedaloft。Butwhencollectedandcondensedbycontrarywinds，itfallsdownwhereverithappenstobemostcondensed。Forthisislikelytohappenwhenthecloudsbeingcarriedalongandmovingwithawindwhichdoesnotallowthemtorest，suddenlyencountersanotherwindandothercloudsfromtheoppositedirection:thereitisfirstcondensed，andwhatisbehindiscarrieduptothespot，andthusitthickens，blackens，andisconglomerated，andbyitsweightitfallsdownandbecomesrain。Such，toallappearance，arethebestofwaters，buttheyrequiretobeboiledandstrained；forotherwisetheyhaveabadsmell，andoccasionhoarsenessandthicknessofthevoicetothosewhodrinkthem。Thosefromsnowandiceareallbad，forwhenoncecongealed，theyneveragainrecovertheirformernature；forwhateverisclear，light，andsweetinthem，isseparatedanddisappears；butthemostturbidandweightiestpartisleftbehind。Youmayascertainthisinthefollowingmanner:Ifinwinteryouwillpourwaterbymeasureintoavesselandexposeittotheopenairuntilitisallfrozen，andthenonthefollowingdaybringitintoawarmsituationwheretheicewillthaw，ifyouwillmeasurethewateragainwhendissolvedyouwillfinditmuchlessinquantity。Thisisaproofthatthelightestandthinnestpartisdissipatedanddriedupbythecongelation，andnottheheaviestandthickest，forthatisimpossible:whereforeIholdthatwatersfromsnowandice，andthosealliedtothem，aretheworstofanyforallpurposeswhatever。Sucharethecharactersofrain-water，andthosefromiceandsnow。