Robert Grosseteste on motion, bodies, and light

ABSTRACT

The article dissects Grosseteste’s theory of the origin of bodily motion discussed in De motu corporali et luce. The first section examines Grosseteste’s discussion of the metaphysical structure of body qua body and the postulation of a kind of original motion (motion qua motion) as a common feature to all bodies. The second section discusses how Grosseteste’s stance on the ontological structure of bodies is connected to his claim that motion qua motion is originated by the apprehensive power as such. The latter is a generic feature common to the apprehensive powers of celestial intelligences, humans, and animals. Finally, the last section of the article analyses Grosseteste’s identification of light with the cause of five kinds of change. Stressing the tensions within his treatment of this problem, I argue that Grosseteste elaborates a remarkably original theory of the ontological structure of the bodies, which stems from his blending of Aristotelian natural philosophy with metaphysical assumptions inherited from the Platonic tradition.

KEYWORDS:

• Natural philosophy
• Grosseteste
• bodily motion
• light
• matter

Acknowledgements

My immense gratitude goes to Neil Lewis and Cecilia Panti for the intense and intriguing discussions of this treatise that we have had over more than three years. I am also grateful to the Ordered Universe project (funded by the Arts and Humanities Research Council UK, AH/N001222/1) for its support in the early stages of the research for this article. A final thank goes to the referees whose comments helped me improve this paper substantively.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Notes

1 The exact order in which Grosseteste’s three treatises were written is still debated. McEvoy tended to posit De luce as the first treatise to be written, followed by De motu corporali et luce, while De lineis would have been written even later in Grosseteste’s production. However, Cecilia Panti’s studies have convincingly proposed a different chronological order, based on systematic and genetic (= use of sources) considerations, by which the three ‘light treatises’ are deeply connected as attempts by Grosseteste to substantiate his theory of light. Accordingly, I will treat De motu corporali et luce as shortly preceding De luce. See McEvoy, The Philosophy of Robert Grosseteste, 516–518; Panti, “Robert Grosseteste and Adam of Exeter’s Physics of Light”; and Panti’s introduction to Grosseteste, La luce, 1–13.

2 Edited by Neil Lewis, a new critical edition of Grosseteste’s De motu corporali et luce is in preparation for the Ordered Universe project.

3 Grosseteste, De motu corporali et luce, 90: “Unum inquantum unum unum solum efficiens est. Nec sic excludo plura efficientia, quorum unum est propinquius et alterum remotius in eodem ordine. Sic, cum dico solum ‘animal’ non excludo substantiam vel particularem substantiam aliam. Igitur motus inquantum est unus unicum efficiens est. Sed motus a principio intrinseco, qui naturalis dicitur, reperitur in omni corpore. Igitur et efficiens proportionatum motui simpliciter reperitur in omni corpore”.

4 Grosseteste displays the same attitude at the beginning of his commentary on Aristotle’s Physics. See for instance, Grosseteste, Commentarius in VIII libros Physicorum Aristotelis, 1. For an overall examination of Grosseteste’s commentary, see also Lewis, “Robert Grosseteste’s Notes on the Physics”. According to PC, the reference to ‘animal’ is much clearer. ‘Animal’ does not exclude either ‘substance’ or ‘individual animal’ because they both correspond to qualifications in the ontological structure of animal, respectively upwards (substance) and downwards (individual animal) in Porphyry’s tree. In virtue of this metaphysical application of Porphyry’s tree, the simple reference to ‘animal’ implies the individual animal (species to individual relation) and its substance (species to genus relation). As substance is predicated of animal and ‘animal’ is predicated of all individual animals, so motion qua motion is predicated of all types of motions and these are predicated of every individual motion. Therefore, the status of motion qua motion is coincides with that of ‘animal’ – a generic feature which is common to all its individuations.

5 If this is the correct horizon of Grosseteste’s reflection in De motu corporali et luce, motion qua motion would be expressed by the types of accidental motions which, in turn, are instantiated and actualised by the individual motions of bodies. Consequently, motion qua motions is the result of a logical abstraction from the types of accidental motion, yet it is also grounded, ontologically, on their instantiations.

6 It might be the case that Grosseteste is implying a stronger reading of PCU applicable to primary substances as well. However, he does not refer to such application anywhere in De motu corporali et luce – or elsewhere, to my knowledge. In turn, he applies PC repeatedly in the text, which points at a weaker reading of PCU as referred primarily to higher order entities.

7 Grosseteste, De motu corporali et luce, 90: “Sed nihil est commune repertum in omni corpore, nisi materia prima et forma prima, et magnitudo, quae necessario consequitur haec duo, et si qua consequuntur magnitudine simpliciter, ut situs et figura.”

8 See Polloni, “Early Robert Grosseteste on Matter”.

9 See Polloni, “Early Robert Grosseteste on Matter”.

10 Grosseteste, De motu corporali et luce, 90: “Sed per magnitudinem, <non> est corpus receptivum motus simpliciter, quod satis patet, ubi ostendit Aristoteles, quod omne, quod movetur, est divisibile. Non igitur secundum magnitudinem, vel aliquid, quod consequitur magnitudinem, est corpus effectivum motus simpliciter. Nec materia prima est efficiens motum, quia ipsa est passiva. Solum igitur necesse est, quod motus simpliciter sit a forma prima, sicut ab efficiente”.

11 Indeed, by keeping the ‘non’ in the text, Grosseteste would claim that magnitude (= three-dimensions) cannot be either agent or patient of movement, since it is neither receptive nor effective of movement. This appears a rather odd outcome, philosophically questionable and textually redundant. It would also follow that prime matter is the patient of simple movement, since prime matter would be the only entity able to receive motion. This would further imply that prime matter is already quantified, since Grosseteste explicitly refers to the divisibility of what is moved, leading to the contradiction of positing matter as extended before being extended.

12 Grosseteste, De motu corporali et luce, 90: “Si motus appropriatus alicuius speciei est natura propria illius, natura autem propria nihil est, nisi forma ordinata ad motus proprios et ad actiones illius speciei, motus simpliciter communis in omni moto exit ab eo, quod commune est in omni specie propria. Et hoc non est, nisi a forma prima”.

13 In turn, if we believe that Grosseteste did not accept the theory of a plurality of non-incidental forms, his reference to the first form can be considered generically, as the function performed by any substantial form. However, a series of incongruencies appear to be implied by this reading of Grosseteste as a monomorphist.

14 See Grosseteste, De motu corporali et luce, 90–91.

15 See McEvoy, The Philosophy of Robert Grosseteste, 280–284; and Panti, “The Quadrivium and the Discipline of Music”, where the author offers a detailed analysis of Grosseteste’s use of this theory. See also Chenu, “Spiritus”.

16 See Panti, “The Quadrivium and the Discipline of Music”, 144–151,

17 See Grosseteste, De intelligentiis, 116.

18 See Avicenna, De medicinis cordialibus, 190; and McEvoy, The Philosophy of Robert Grosseteste, 280–284.

19 See Avicenna, De medicinis cordialibus, 194: “Sed in qualitate, hoc est, ut complexio eius sit optima et lux eius sit maxima et sit simillima substantiae caeli”. This point is very close to Galen’s doctrine of light-like pneuma. For instance, see Galen, De placitis Hippocratis et Platonis, VII, 7, 24–26. See also Lindberg, Theories of Vision, 9–11. It should be noted that Grosseteste’s theory might have been influenced also by Augustine, as Neil Lewis signalled to me and has also been mentioned by McEvoy. See Augustine, De Genesi ad Litteram, XII.16; and McEvoy, The Philosophy of Robert Grosseteste, 278–289.

20 See Grosseteste, De motu corporali et luce, 91.

21 It is unclear whether Grosseteste here is referring to one or more unmoved movers, as the text is quite tricky in this regard. Considering his general attitude as exposed in further works, it seems plausible to suppose that there is a plurality of unmoved movers, in accordance to Physics VIII.

22 See Grosseteste, Hexaemeron, 117–120.

23 See Grosseteste, De motu corporali et luce, 91.

24 See Grosseteste, De motu corporali et luce, 91: “Item, cum tam apprehensiva, quam virtus corporalis ponendae sint in ordine efficientium motum caeli et animalium, necesse est, ut altera ponatur prior et remotior a motu, reliqua posterior et propinquior motui. Illa autem, quae prior est, motiva erit posterioris et non e contrario. Sed dignius est, ut virtus incorporalis pura sit motiva virtutis corporalis, quam e contrario. In his ergo est primum motivum apprehensiva. Ergo et simpliciter motus erit apprehensiva primum efficiens”.

25 See Grosseteste, De motu corporali et luce, 91- 92.

26 Grosseteste’s mention of ‘order and position’ of bodies as the end of motion qua motion seems to be a reference to the order of the universe. Unfortunately, he does not expand on this aspect sufficiently as to further substantiate this point.

27 See Avicenna, De anima, I, 86. On the Latin reception of this meaningful passage, see Perler, “Why is the Sheep Afraid of the Wolf?”

28 See Grosseteste, Hexaemeron, 109 and 118–119.

29 See McEvoy, The Philosophy of Robert Grosseteste, 280–284.

30 Grosseteste, De motu corporali et luce, 92: “Dico enim, quod forma prima corporalis est primum motivum corporale. Illa autem est lux, quae cum se multiplicat et expandit absque hoc, quod corpulentiam materiae secum moveat, eius pertransitio per diaphanum fit subito et non est motus, sed mutatio. Quando vero est lux expandens se in partes diversas, ista incorporatur materiae, si corpulentiam materiae secum extendit, et fit rarefactio materiae vel augmentum. Quando vero congregatur lux in se cum corpulentia materiae, fit condensatio vel diminutio. Cum vero lux secundum unam viam se generat secum trahens materiam, fit motus localis. - Cum vero lux, quae est intra materiam, mittatur foras et quod foris est, immittit intus, fit alteratio. Et in hoc patet, quod motio corporalis est vis multiplicativa lucis. Et hoc idem est appetitus corporalis et naturalis”.

31 See Polloni, “Early Grosseteste on Matter”.

32 See Ibn Gabirol, Fons vitae, 62–63.

33 On this point, see Trifogli, “Roger Bacon on Substantial Change”.

34 In fact, there is no way to refer to the materia nuda (‘bare matter’) since prime matter is never deprived of forms in nature. See Grosseteste, Commentarius in VIII libros Physicorum, 108–109.

35 On Grosseteste’s theory of light, see Dinkova-Bruun et al., The Dimensions of Colour, 21–25.

36 See Grosseteste, De luce, 226.

37 See Grosseteste, De luce, 227.

38 See Ibn Gabirol, Fons vitae, 118. See also Polloni, The Twelfth-Century Renewal, 147–150.

39 Ibn Gabirol, Fons vitae, 243–245: “Similiter et lumen quod est diffusivum in hyle; hoc est quia hyle, quo magis descenderit, constringitur et corporatur, et partes eius mediae prohibebunt ultimas partes perfecte penetrari lumine … Similiter est dicendum de lumine quod est infusum in materia, hoc est quia, quo fuerit purius et clarius et liberius a materia, erit perfectius et fortius. Similiter etiam, quo magis fuerit commixtum clariori parti materiae, amplius servabit speciem suam, et est fortius et firmius quam illud quod est commixtum crassiori parti eius … Et secundum hanc considerationem debet ut diminutio luminis substantiarum et diversitas non sit propter lumen in se, sed propter materiam, quia est corporalis comparatione formae, sicut iam praedictum est”. English translation by Laumakis, The Font of Life, 207.

40 See Grosseteste, De luce, 231–232.

41 On whether Grosseteste’s theory of light should be interpreted as metaphysical or physical, see Speer, “Physics or Metaphysics?”