Ibn-al-Haitam, al-Hasan Ibn-al-Hasan; Witelo; Risner, Friedrich, Opticae thesavrvs Alhazeni Arabis libri septem, nunc primùm editi. Eivsdem liber De Crepvscvlis & Nubium ascensionibus. Item Vitellonis Thuvringopoloni Libri X. Omnes instaurati, figuris illustrati & aucti, adiectis etiam in Alhazenum commentarijs, a Federico Risnero, 1572

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          <p>
            <s xml:id="echoid-s1232" xml:space="preserve">
              <pb o="20" file="0026" n="26" rhead="ALHAZEN"/>
            luce ſolis aut diei, uenient formæ eorum ad uiſum admixtæ cum forma lucis fortis orientis ſuper
              <lb/>
            ipſas, & comprehendet uiſus formam huiuſmodi rerũ uiſarum admixtam cum forma lucis fortis.</s>
            <s xml:id="echoid-s1233" xml:space="preserve">
              <lb/>
            Quare ſuperabit forma lucis fortis formam debilem.</s>
            <s xml:id="echoid-s1234" xml:space="preserve"> Et multoties latet lux debilis, & forma rei ui-
              <lb/>
            ſæ debilis, quando peruenerit in uiſum lux fortis, quamuis nõ ſit peruentus duarum formarum ad
              <lb/>
            uiſum ex una uerticatione.</s>
            <s xml:id="echoid-s1235" xml:space="preserve"> Et hoc erit, quãdo peruentus duarum formarum fuerit ex duabus uer-
              <lb/>
            ticationibus uicinantibus.</s>
            <s xml:id="echoid-s1236" xml:space="preserve"> Et hoc apparet nocte, & in luce ignis.</s>
            <s xml:id="echoid-s1237" xml:space="preserve"> Quoniam uiſus quando compre-
              <lb/>
            henderit lucem ignis, & fuerit ignis propinquus uiſui, & fuerit lux eius fortis, & fuerit in oppoſi-
              <lb/>
            tione uiſus in illa diſpoſitione aliquod uiſibile, in quo eſt lux debilis accidentalis, & fuerit illud ui-
              <lb/>
            ſibile remotius à uiſu quàm ignis, & fuerit ſuper uerticationem uicinãtem uerticationi ignis:</s>
            <s xml:id="echoid-s1238" xml:space="preserve"> tunc
              <lb/>
            uiſus non comprehendet uiſibile illud comprehenſione uera.</s>
            <s xml:id="echoid-s1239" xml:space="preserve"> Et ſi aſpiciens cooperuerit ignem à
              <lb/>
            ſuo uiſu, aut remouerit ſe à uerticatione ignis, ita ut ſit uerticatio, à qua comprehendet illud uiſibi-
              <lb/>
            le, remota à uerticatìone ignis:</s>
            <s xml:id="echoid-s1240" xml:space="preserve"> tunc comprehendet illud uiſibile comprehenſione manifeſtiore.</s>
            <s xml:id="echoid-s1241" xml:space="preserve">
              <gap/>
            Et
              <lb/>
            cauſſa illius eſt, quòd uiſibile, in quo eſt lux debilis accidentalis, habet formam obſcuram, & cum
              <lb/>
            ipſam comprehenderit uiſus, non autem comprehenderit cum ea lucem fortem:</s>
            <s xml:id="echoid-s1242" xml:space="preserve"> ſentiet lucem de-
              <lb/>
            bilem, in qua eſt aliquid obſcuritatis inter uiſum, aut priuationem lucis fortis à parte eius, in quam
              <lb/>
            peruenit lux debilis.</s>
            <s xml:id="echoid-s1243" xml:space="preserve"> Et cum uiſus comprehenderit formam lucis debilis, & comprehenderit cum
              <lb/>
            ea lucem fortem:</s>
            <s xml:id="echoid-s1244" xml:space="preserve"> tunc etiam comprehendet lucem fortem in parte contingente partem uiſus, qua
              <lb/>
            comprehendebat formam obſcuram:</s>
            <s xml:id="echoid-s1245" xml:space="preserve"> non comprehendet autem uiſus lucem debilem, quæ eſt in
              <lb/>
            forma obſcura propter duo:</s>
            <s xml:id="echoid-s1246" xml:space="preserve"> quorum unum eſt, quòd lux fortis, quando peruenerit ad uiſum, illu-
              <lb/>
            minatur totus uiſus, & cum totus uiſus fuerit illuminatus, non apparebit in eo lux debilis, & maxi-
              <lb/>
            mè quando lux debilis füerit proportionis minimæ reſpectu lucis fortis.</s>
            <s xml:id="echoid-s1247" xml:space="preserve"> Alterum eſt coniunctio
              <lb/>
            lucis debilis cum luce forti in duabus partibus uiſus uicinãtibus, & quia lux debilis reſpectu lucis
              <lb/>
            fortis eſt ferè obſcuritas.</s>
            <s xml:id="echoid-s1248" xml:space="preserve"> Et cum lux appropin quabit ad formam obſcuram debilem, & forma lucis
              <lb/>
            fortis fuerit in uiſu:</s>
            <s xml:id="echoid-s1249" xml:space="preserve"> non comprehendet uiſus formam, quæ eſt in luce obſcura, neque comprehen-
              <lb/>
            det etiam formam obſcuram, niſi obſcuritatem tantùm:</s>
            <s xml:id="echoid-s1250" xml:space="preserve"> & ſic non diſtinguetur ab eo forma, neque
              <lb/>
            comprehendet eam comprehenſione uera.</s>
            <s xml:id="echoid-s1251" xml:space="preserve"> Et occultatio formarum debilis lucis propter uicinita-
              <lb/>
            tem lucis fortis, habet ſimile in coloribus:</s>
            <s xml:id="echoid-s1252" xml:space="preserve"> quoniam color fuſcus ſi intingatur cũ corpore albo pun-
              <lb/>
            ctatim, apparebunt ipſa puncta nigra propter fortitudinem albedinis:</s>
            <s xml:id="echoid-s1253" xml:space="preserve"> & ſi eadẽ puncta fuerint po-
              <lb/>
            ſita ſupra corpora ualde nigra, apparebunt ferè alba, & non apparebit obſcuritas, quæ eſt in eis.</s>
            <s xml:id="echoid-s1254" xml:space="preserve"> Et
              <lb/>
            quando illa tinctura fuerit in corporibus, quæ non ſunt multùm alba, neque multùm nigra:</s>
            <s xml:id="echoid-s1255" xml:space="preserve"> appa-
              <lb/>
            rebit color ſecundum ſuum eſſe.</s>
            <s xml:id="echoid-s1256" xml:space="preserve"> Et ſimiliter quando color uiridis ſegetalis fuerit ſuper corpus ci-
              <lb/>
            trinum, apparebit illa tinctura obſcura:</s>
            <s xml:id="echoid-s1257" xml:space="preserve"> & quando fuerit in corpore nigro, apparebit illa tinctura
              <lb/>
            ſimilis colori origani.</s>
            <s xml:id="echoid-s1258" xml:space="preserve"> Et ſimiliter eſt omnis tinctura media inter duas extremitates.</s>
            <s xml:id="echoid-s1259" xml:space="preserve"> Viſibilia ergo
              <lb/>
            uicinantia, quando fuerint remota in fortitudine & debilitate coloris:</s>
            <s xml:id="echoid-s1260" xml:space="preserve"> quod eſt debilis coloris, la-
              <lb/>
            tebit uiſum:</s>
            <s xml:id="echoid-s1261" xml:space="preserve"> quoniam qualitates lucis & coloris non comprehenduntur à uiſu, niſi reſpectu eorum
              <lb/>
            inter ſe.</s>
            <s xml:id="echoid-s1262" xml:space="preserve"> Et lux fortis non prohibebit uiſum à comprehenſione uiſibilium lucis debilis, niſi pro-
              <lb/>
            pter admixtionem formæ lucis debilis cum formis eorum, & propter uictoriam formarum lucis
              <lb/>
            fortis ſuper formas lucis debilis, & debilitatem ſenſus ad comprehendendum illud, quod eſt mini-
              <lb/>
            mæ proportionis, reſpectu fortis.</s>
            <s xml:id="echoid-s1263" xml:space="preserve"> Iam ergo compleuimus declarationem omnium rerum depen-
              <lb/>
            dentium ab illo capitulo.</s>
            <s xml:id="echoid-s1264" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div43" type="section" level="0" n="0">
          <head xml:id="echoid-head62" xml:space="preserve">DE OFFICIO ET VTILITATE INSTRVMEN-
            <lb/>
          torum uiſus. Caput ſextum.</head>
          <head xml:id="echoid-head63" xml:space="preserve" style="it">33. Multiplex & uaria eſt partium uiſ{us} utilit{as}: diuerſa́ ſunt ipſarum inter
            <lb/>
          ipſas officìa. 4 p 3.</head>
          <p>
            <s xml:id="echoid-s1265" xml:space="preserve">TVnicæ, quas diximus in declaratione formæ uiſus, ſunt inſtrumenta, per quæ completur ui-
              <lb/>
            ſio.</s>
            <s xml:id="echoid-s1266" xml:space="preserve"> Tunica uerò prima, quæ dicitur cornea, eſt tunica diaphana, & nõnihil fortis, & eſt ſuper-
              <lb/>
            poſita foramini, quod eſt in anteriori uueæ.</s>
            <s xml:id="echoid-s1267" xml:space="preserve"> Et prima utilitas eius eſt, quòd cooperit foramen
              <lb/>
            uueæ:</s>
            <s xml:id="echoid-s1268" xml:space="preserve"> quare retinet humorem albugineum, qui eſt in anteriori uueæ:</s>
            <s xml:id="echoid-s1269" xml:space="preserve"> & eſt diaphana, ut tranſeant
              <lb/>
            in ea formæ lucis & coloris ad interius uiſus:</s>
            <s xml:id="echoid-s1270" xml:space="preserve"> quoniam non tranſeunt, niſi per diaphana.</s>
            <s xml:id="echoid-s1271" xml:space="preserve"> Fortitudo
              <lb/>
            autem eius eſt, ut non corrumpatur citò:</s>
            <s xml:id="echoid-s1272" xml:space="preserve"> quoniam eſt expoſita aeri, & poteſt citò corrumpi ex fu-
              <lb/>
            mo, & puluere, & ſimilibus.</s>
            <s xml:id="echoid-s1273" xml:space="preserve"> Humor autem albugineus eſt diaphanus, & eſt humidus & fluxibilis.</s>
            <s xml:id="echoid-s1274" xml:space="preserve">
              <lb/>
            Diaphanus autem eſt, ut pertranſeant in eo formæ, & perueniant in eo ad humorem glacialem:</s>
            <s xml:id="echoid-s1275" xml:space="preserve">
              <lb/>
            humiditas autem eius eſt, ut ſemper humefaciat humorem glacialem, ita ut eius natura ſit cu-
              <lb/>
            ſtodita:</s>
            <s xml:id="echoid-s1276" xml:space="preserve"> quoniam tela, quæ eſt ſuper glacialem, eſt ualde tenuis, & nimia ſiccitate poteſt cor-
              <lb/>
            rumpi.</s>
            <s xml:id="echoid-s1277" xml:space="preserve"> Tunica autem nigra continens humorem albugineum, quæ eſt uuea, eſt nigra, & fortis,
              <lb/>
            ſpiſſa, & ſphærica:</s>
            <s xml:id="echoid-s1278" xml:space="preserve"> & in anteriori eius eſt foramen rotundum, ſicut narrauimus.</s>
            <s xml:id="echoid-s1279" xml:space="preserve"> Nigredo ue-
              <lb/>
            rò eius eſt, ut obſcuretur humor albugineus & glacialis, ita ut appareant in eis formæ lucis debi-
              <lb/>
            lis:</s>
            <s xml:id="echoid-s1280" xml:space="preserve"> quoniam lux debilis üalde apparet in locis obſcuris, & latet in locis luminoſis.</s>
            <s xml:id="echoid-s1281" xml:space="preserve"> Et eſt aliquan-
              <lb/>
            tulum fortis, ut retineat humorem albugineum, & ut non reſudet ex eo aliquid foras.</s>
            <s xml:id="echoid-s1282" xml:space="preserve"> Et eſt ſpiſſa,
              <lb/>
            ut ſit obſcura:</s>
            <s xml:id="echoid-s1283" xml:space="preserve"> quoniam ſi eſſet rara, eſſet diàphana:</s>
            <s xml:id="echoid-s1284" xml:space="preserve"> ſed cum fuerit ſpiſſa, obſcurabitur anterior pars
              <lb/>
            eius.</s>
            <s xml:id="echoid-s1285" xml:space="preserve"> Et eſt ſphærica, quia magis temperata figurarum eſt ſphærica, & eſt magis remota ab offen-
              <lb/>
            ſionibus:</s>
            <s xml:id="echoid-s1286" xml:space="preserve"> habens enim angulos, citius alteratur per angulos.</s>
            <s xml:id="echoid-s1287" xml:space="preserve"> Foramen autem, quod eſt in a
              <gap/>
            te-
              <lb/>
            </s>
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