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-s1176" xml:space="preserve">
              <pb o="19" file="0025" n="25" rhead="OPTICAE LIBER I."/>
            non ualde album, ſicut comprehendit corpus album in umbra.</s>
            <s xml:id="echoid-s1177" xml:space="preserve"> Quare non diſtinguetur ab eo for-
              <lb/>
            ma.</s>
            <s xml:id="echoid-s1178" xml:space="preserve"> Et omne hoc erit ita, quando lux, quæ eſt in corpore colorato, fuerit fortis, & forma, quæ oritur
              <lb/>
            ab eo ſuper corpus oppoſitum, fuerit albedinis debilis.</s>
            <s xml:id="echoid-s1179" xml:space="preserve"> Si autem lux, quæ eſt in corpore colorato,
              <lb/>
            fuerit debilis:</s>
            <s xml:id="echoid-s1180" xml:space="preserve"> tunc forma, quæ exit ab eo ſuper corpus oppoſitum, erit obſcura, & erit apud uiſum,
              <lb/>
            ſicut colores, quos comprehendit in locis obſcuris, in quibus eſt lux ualde debilis, & quaſi colores
              <lb/>
            corporum diaphanorum, ſuper quæ oritur lux debilis.</s>
            <s xml:id="echoid-s1181" xml:space="preserve"> Formæ ergo colorum, quæ ſunt in corpori-
              <lb/>
            bus coloratis, quando lux, quæ eſt ſuper ipſa, fuerit debilis, quando oriuntur ſuper corpora oppoſi-
              <lb/>
            ta ſibi, non erunt, niſi umbræ tantùm quo ad ſenſum uiſus.</s>
            <s xml:id="echoid-s1182" xml:space="preserve"> Et ſi corpus oppoſitum colori fuerit in
              <lb/>
            loco obſcuro, nihil apparebit ſuper ipſum propter ſuam obſcuritatẽ, & obſcuritatem formæ uenien
              <lb/>
            tis ad ipſum.</s>
            <s xml:id="echoid-s1183" xml:space="preserve"> Et ſi corpus oppoſitũ illi colori fuerit in illuminato loco, & fuerit ſuper ipſum lux, præ
              <lb/>
            ter lucẽ illius formæ, & fuerit illud corpus illuminatum:</s>
            <s xml:id="echoid-s1184" xml:space="preserve"> apparebit color eius ſuper iſtam formam,
              <lb/>
            & apparebit uiſui color iſtius corporis, & nõ apparebit forma:</s>
            <s xml:id="echoid-s1185" xml:space="preserve"> quoniam eſt ſicut umbra, & non di-
              <lb/>
            ſtinguetur à uiſu iſta diminutio.</s>
            <s xml:id="echoid-s1186" xml:space="preserve"> Et ſi iſtud corpus, ſuper quod eſt forma, fuerit album, & præterea
              <lb/>
            fuerit illuminatum cum alio lumine, præter lumen formæ:</s>
            <s xml:id="echoid-s1187" xml:space="preserve"> tunc forma obſcurabit albedinem iſtius
              <lb/>
            corporis, & lucem eíus tantùm propter ſuam obſcuritatem, ſicut faciũt umbræ in corporibus alijs:</s>
            <s xml:id="echoid-s1188" xml:space="preserve">
              <lb/>
            & formæ, quæ ſunt huiuſmodi, tantùm comprehẽduntur à uiſu ſuper corpora oppoſita coloribus.</s>
            <s xml:id="echoid-s1189" xml:space="preserve">
              <lb/>
            Viſus ergo non comprehendit formam coloris ſuper corpus oppoſitum colori, niſi quando forma
              <lb/>
            ſecũda ueniens ad ipſum ex forma coloris, fuerit fortior, & potẽtior prima forma ueniẽte ad ipſam
              <lb/>
            cum ea, ex luce & colore, quæ ſunt in corpore, ſuper quod eſt forma.</s>
            <s xml:id="echoid-s1190" xml:space="preserve"> Et iſte modus eſt ualde rarus:</s>
            <s xml:id="echoid-s1191" xml:space="preserve">
              <lb/>
            & propter hoc rarò apparet huiuſmodi forma, & non apparet ex ea, niſi illud, quod eſt ex coloribus
              <lb/>
            fortibus ſcintillantibus.</s>
            <s xml:id="echoid-s1192" xml:space="preserve"> Et ſimiliter quòd lux debilis, nõ apparet ſuper corpus oppoſitum ſibi:</s>
            <s xml:id="echoid-s1193" xml:space="preserve"> eſt:</s>
            <s xml:id="echoid-s1194" xml:space="preserve">
              <lb/>
            quia corpus oppoſitũ luci debili, quando fuerit illuminatũ ab alio lumine, admiſcebuntur duæ lu-
              <lb/>
            ces, & ſic non diſtinguetur lux debilis à uiſu.</s>
            <s xml:id="echoid-s1195" xml:space="preserve"> Et cũ corpus oppoſitum luci debili fuerit obſcurum,
              <lb/>
            non apparebit forma lucis debilis ſuper ipſum:</s>
            <s xml:id="echoid-s1196" xml:space="preserve"> quoniam forma lucis debilior eſt ipſa luce:</s>
            <s xml:id="echoid-s1197" xml:space="preserve"> & forma
              <lb/>
            ſecunda ueniens ad oculũ ab iſta forma, ex qua oportet uiſum comprehẽdere iſtam formam ſuper
              <lb/>
            corpus oppoſitũ luci, eſt debilior iſta forma.</s>
            <s xml:id="echoid-s1198" xml:space="preserve"> Cum ergo lux fuerit debilis, & corpus oppoſitũ fuerit
              <lb/>
            obſcurum:</s>
            <s xml:id="echoid-s1199" xml:space="preserve"> erit forma;</s>
            <s xml:id="echoid-s1200" xml:space="preserve"> quæ eſt ſuper corpus oppoſitũ, ualde debilis, & erit forma ſecũda, quæ uenit
              <lb/>
            exilla, in fine debilitatis.</s>
            <s xml:id="echoid-s1201" xml:space="preserve"> Viſus autẽ non comprehendit lucẽ, quæ eſt in fine debilitatis.</s>
            <s xml:id="echoid-s1202" xml:space="preserve"> Formæ ergo
              <lb/>
            omnium colorũ illuminatorum, & formæ omnis lucis oriuntur ſuper corpora oppoſita, & nõ appa
              <lb/>
            rent pleræq;</s>
            <s xml:id="echoid-s1203" xml:space="preserve"> illarũ propter cauſſas, quas diximus:</s>
            <s xml:id="echoid-s1204" xml:space="preserve"> & quædã apparent, quando fuerint ſecundũ mo-
              <lb/>
            dum, quem narrauimus.</s>
            <s xml:id="echoid-s1205" xml:space="preserve"> Iam ergo declarata eſt cauſſa, propter quã non comprehẽdit uiſus formas
              <lb/>
            omnium colorũ, quæ ſunt in corporibus coloratis ſuper omnia corpora oppoſita illi, & cõprehen-
              <lb/>
            dit quaſdã:</s>
            <s xml:id="echoid-s1206" xml:space="preserve"> & cum hoc comprehẽdit omnes colores, qui ſunt in corporibus coloratis.</s>
            <s xml:id="echoid-s1207" xml:space="preserve"> Et cauſſa eſt,
              <lb/>
            quia comprehendit colores, qui ſunt in corporibus coloratis ex propria forma ueniente ad ipſum
              <lb/>
            ex eis, quæ eſt fortior forma ſecunda ueniente ad ipſum ex formis colorum, qui ſunt ſuper corpora
              <lb/>
            oppoſita illi.</s>
            <s xml:id="echoid-s1208" xml:space="preserve"> Et comprehendit etiã formam colorum ſingularẽ non admixtam cum alia:</s>
            <s xml:id="echoid-s1209" xml:space="preserve"> & compre-
              <lb/>
            hendit ſecundã formam uenientẽ ad ipſum ex formis colorum admixtam cum alia.</s>
            <s xml:id="echoid-s1210" xml:space="preserve"> Et hoc eſt quod
              <lb/>
            promiſimus declarare in fine capitis tertij.</s>
            <s xml:id="echoid-s1211" xml:space="preserve"> Et declaratũ eſt modò, quòd colores, quos comprehen-
              <lb/>
            dit uiſus ex rebus uiſis, non comprehendit, niſi admixtos cũ formis lucis, quæ ſunt in eis, & admix-
              <lb/>
            tos cum omnibus formis orientibus ſuper ipſos ex coloribus corporum oppoſitorum.</s>
            <s xml:id="echoid-s1212" xml:space="preserve"> Et ſi in cor-
              <lb/>
            pore diaphano, quod eſt medium inter ipſos & uiſum, fuerit aliqua ſpiſsitudo, admiſcebitur color
              <lb/>
            eius etiam cum eis, & uiſus non comprehendit illum colorem ſingularem:</s>
            <s xml:id="echoid-s1213" xml:space="preserve"> ſed tamen formæ, quæ
              <lb/>
            oriuntur ſuper corpora colorata, ſunt in maiori parte ualde debiles:</s>
            <s xml:id="echoid-s1214" xml:space="preserve"> & formæ ſecũdæ, quæ ueniunt
              <lb/>
            ex eis ad uiſum, ſunt in fine debilitatis:</s>
            <s xml:id="echoid-s1215" xml:space="preserve"> & propter hoc erunt colores ipſorum corporum plerunque
              <lb/>
            fortiores formis orientibus ſuper ipſa.</s>
            <s xml:id="echoid-s1216" xml:space="preserve"> Et ſimiliter ſi in corpore diaphano, quod eſt inter uiſuin &
              <lb/>
            rem uiſam, fuerit modica ſpiſsitudo, non diſtinguetur à uiſu color eius à colore uiſi uenientis cum
              <lb/>
            eo, quando color uiſi uenientis cum eo, fuerit fortior colore illius.</s>
            <s xml:id="echoid-s1217" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div42" type="section" level="0" n="0">
          <head xml:id="echoid-head61" xml:space="preserve" style="it">32. Lux uehemens trib{us} potißimùm de caußis uiſibilia quædam obſcur at. Vide 2 n.</head>
          <p>
            <s xml:id="echoid-s1218" xml:space="preserve">QVare uerò lux fortis prohibeat uiſum à comprehẽſione quarundam rerũ uiſarum:</s>
            <s xml:id="echoid-s1219" xml:space="preserve"> eſt:</s>
            <s xml:id="echoid-s1220" xml:space="preserve"> quia
              <lb/>
            formæ, quæ ueniunt ad uiſum ſuper unam uerticationem, non comprehẽduntur à uiſu, niſi
              <lb/>
            admixtæ.</s>
            <s xml:id="echoid-s1221" xml:space="preserve"> Et cum quæ dam formæ admixtæ fuerint fortis ſcintillationis, & quædam debi-
              <lb/>
            lis, ſuperabit forma fortis formam debilem, & ſic nõ comprehendetur forma debilis à uiſu.</s>
            <s xml:id="echoid-s1222" xml:space="preserve"> Et cum
              <lb/>
            formæ admixtæ fuerint propinquæ in fortitudine, comprehendentur à uiſu, & erit comprehenſio
              <lb/>
            cuiuslibet illarum ſecundum illud, quod permiſcebitur cum eis ex formis admixtis cum eis:</s>
            <s xml:id="echoid-s1223" xml:space="preserve"> quo-
              <lb/>
            niam formæ admixtæ non comprehenduntur à uiſu ſingulariter, ſed admixtæ.</s>
            <s xml:id="echoid-s1224" xml:space="preserve"> Stellæ ergo non
              <lb/>
            comprehenduntur à uiſu in luce diei, quia lux, quæ peruẽnit in aerem, eſt fortior luce ſtellarum.</s>
            <s xml:id="echoid-s1225" xml:space="preserve">
              <lb/>
            Cum ergo inſpiciens aſpexerit cœlum in luce diei:</s>
            <s xml:id="echoid-s1226" xml:space="preserve"> erit aer, qui eſt inter ipſum & cœlum, illu-
              <lb/>
            minatus à luce ſolis, & continuatur cum uiſu, & erunt ſtellæ ex poſteriori illius lucis.</s>
            <s xml:id="echoid-s1227" xml:space="preserve"> Venient
              <lb/>
            ergo forma ſtellæ, & forma lucis, quæ eſt in aere medio inter uiſum & ſtellam, ad uiſum
              <lb/>
            ſuper unam uerticationem:</s>
            <s xml:id="echoid-s1228" xml:space="preserve"> & ſic comprehendentur admixtæ.</s>
            <s xml:id="echoid-s1229" xml:space="preserve"> Sed forma lucis diei eſt in ae-
              <lb/>
            re fortior multò forma lucis ſtellæ:</s>
            <s xml:id="echoid-s1230" xml:space="preserve"> quare ſuperabit lux aeris lucem ſtellæ, & ſic non diſtin-
              <lb/>
            guetur forma ſtellæ.</s>
            <s xml:id="echoid-s1231" xml:space="preserve"> Et ſimiliter eſt lux debilis, quæ eſt in medio lucis fortis, ſicut ignis de-
              <lb/>
            bilis in luce ſolis, & ſicut noctiluca in luce diei, & ſimilibus:</s>
            <s xml:id="echoid-s1232" xml:space="preserve"> iſta enim uiſibilia quando fuerint in
              <lb/>
            </s>
          </p>
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