In dense

matter the

species has

more per

manence than in rare.

accidit in praedictis1 multum debilitat lucem. Sed a parte solis non est nisi una fractio et illa est debilis, quia variatio diaphani in sphaera coelesti et sphaera ignis non est tanta sicut est crystalli et aeris. Item in raro est dispersio corporalium partium, et ideo species multum dispergitur et non unitur, et non colliguntur multa in parvo loco sicut in denso. Quapropter oportet quod sit debilis operationis, et ideo in libro de Causis dicitur quod virtus dispersa est debilis operationis, et ideo haec est causa quare non potest diu conservare se in raro quamvis in denso.

Alia causa est, quia ab omni puncto aeris lucidi fit multiplicatio lucis secundum omnes diametros, et ideo quando est magna quantitas sicut accidit in raro, quasi sine comparatione est major dispersio speciei ab eo quam a denso, et ista multiplicatio infinita inducit debilitationem speciei, praecipue cum sit in materia aliena. Et quia debilitatur multum per actionem exteriorem, accidit quod non potest se conservare in materia in qua est, et ideo deficit in potentia materiae. Et his de causis potest natura medii diaphani specifica invalescere super speciem debilitatem et corrumpitur statim necessario post generationem sine tempore sensibili intercepto.

Sed in denso potest diu manere et intendi propter rationes contrarias, ut in luna et stellis, dum radiositas solis sit praesens eis, quia in parvo loco multum de specie colligitur et a parva quantitate respectu rari, quod tantum haberet de substantia dispersa quod sit modica dispersio per multitudinem exteriorem; et ideo fortificatur species et intenditur in tali denso, et non corrumpitur nisi per privationem actionis agentis. Unde luna et stellae semper lucent nisi per eclipsin, et ideo haec est causa duplex, quare densum bene retinet lucem et hujusmodi species, quia bene incorporantur in eo, et non sic in raro. Si dicatur quod in regionibus sub Cancro et alibi est magis combustio elementaris, et est ibi mala habitatio nec continua, ut dicit Ptolemaeus libro de Dispositione Sphaerae, quapropter manebunt species et continuabuntur sine corruptione; dicendum est, quod non oportet, quia licet corrumpantur quasi infinities illic in die sicut hic,

1i. e. as we saw previously: e. g. in p. 536 and elsewhere.

tamen aer ibi propter magnam moram solis super capita eorum quasi per quatuor dies, ut dicit Ptolemaeus propter parvitatem declinationum solis equidistantium1, recipit majorem dispositionem ad combustionem quam hic. Sicut videmus quod propter moram solis magnam accidit in aere nostro; quod prope finem octavae horae et principium nonae est major calor quam in sexta hora, quando magis appropinquat capitibus nostris. Quamvis ergo species corrumpatur successive quaelibet, tamen relinquit ex sua praesentia aliquam dispositionem caloris, et sic potest plus et plus calor augmentari propter moram solis super eundem aerem. Si etiam dicatur, quod cum rara non retinent species sed densa, tunc terra et ligna et lapides et hujusmodi deberent magis abundare in specie lucis et per consequens in calore quam aer, potest dici quod hujusmodi densa exterius habent magis de his quam aer et aqua et perspicua, ut in partibus exterioribus apparet quando tangimus ea. Nam lapidem expositum soli magis calidum sentimus quam aerem, et magis etiam visibilis est ex praesentia lucis quam aer, quia solum densum natum est terminare visum. Sed in partibus interioribus densi non sic est, neque quantum ad visum, neque quantum ad tactum, quando aerem percipimus visu in profundo et calorem ejus sentimus. quia de facili recipit speciem per sui profundum; sed densum non sic, quia difficulter recipit speciem propter sui compactionem, licet bene retineat, postquam receperit.

Videlicet hoc est intendendum in istis rebus inferioribus corporalibus. In rebus vero incorporalibus potest vera species animae compleri in effectum completum sine destructione patientis. [Nam] natum est ad hujus effectum de natura sua; ut stellae et luna natae sunt habere lucem perfectam quam exigit natura sua, licet sol plus habeat de luce. Et tunc in principio fit species lucis usque ad lunam et stellas, et postea completur in eis sicut fuit a prima creatione, et sicut.

1 solis confusionem equidistantiam, J.

2 This is clearly intended, though the MSS. give exterioribus.

3 The passage from this point to the end of the treatise is omitted by Jebb, and is not found in the Oxford MS. I take it from the much older MS. Reg.

post eclipses stellarum accidit; nam primo debilitatam habent lucem, tanquam similem et speciem, et post hoc claram et completam. Cujus signum est quod luna videtur in eclipsi rubea, et quod exit in umbra; et quando est in umbra habet speciem lucis debitae quae venit de luce transeunte per latera et fines umbrae, sicut postea1 magis explanabitur.

Veruntamen sciendum quod species solis quae est de vera ejus substantia non potest compleri in luna et stellis, licet in eis fiat: quia tunc oporteret lumen et stellas fieri solem, quod est impossibile. Lux enim est quantitas communis soli et stellis et igni, licet magis sit in sole; et ideo potest species lucis compleri in luna et stellis, et non species similis soli; quia sol et luna et stellae durant in sua substantia, sicut posterioribus erit manifestum. Et lux non est de eorum substantia, sed est aeris communis eis et igni; licet aliquando solebant dicere lucem esse formam substantialem solis et stellarum. Sed hoc est falsum 2.

1 Cf. pp. 104-5 of this volume. It is probable, however, that the reference here, and a few lines lower down, is to a subsequent section of the work, of which the present treatise is but a portion.

2 The treatise here ends with the words 'Explicit tractatus fratris R. Bacoun de multiplicatione specierum.' In another and more recent handwriting the words are added, ' Post istum tractatum sequi debet perspectiva.' The fact that this treatise was sent to the Pope at the same time as the Opus Majus accounts for its having been incorporated into that work by the transcriber of O. (followed by D.). Though there are references in it, like that on p. 408, which imply that it was a portion of an encyclopaedic treatise, partly written, partly projected, yet there are other references, like that on p. 534, to the Opus Majus itself. These I incline to regard as glosses, added perhaps by Bacon's pupils or transcribers.

The scholastic style of the work contrasts strongly with that of the Opus Majus, which, as we know, was a Persuasio Praeambula. It has been less studied than Bacon's other works, not so much from its difficulty as from the notion that it was a mere recast of Aristotelian Physics, and from the further notion that Aristotelian Physics were not worth studying. Both of these positions, I venture to think, will be abandoned, when the same attention shall have been given to the history of science that has been given during the last half century to other departments of Evolution. What lifts Bacon's discussions upon force to a higher level than that of barren dialectical debate is, that they were animated by constant reference to a living and growing science due to the later Greeks, and still more to the Arabians, the science of Optic, including the study of the organs of vision and perception no less than that of the force acting on them. For Bacon the radiation of light was a type of all other radiant forces.

INDEX