Changes Of The Transfiguration

Ecce ipsa transfiguratio. Describit autem eam dupliciter, in Domino videlicet, et testibus, qui in monte fuerunt. In ipso autem dupliciter, in corpore Domini et in amictu. In corpore autem describit dupliciter, in communi et in speciali determinando modos eius. In communi autem dicit cum autem figura sit terminatio quantitatis, hoc modo non mutavit figuram Dominus; sed dicitur hic figura physici corporis, quae est cum colore et passionibus, quae transfigurata est, quando actus altioris potestatis in ea apparuit. Id enim, quod in corpore humano secundum potestatem qualitatum complexionalium apparet, color est humanus. Sed quia corpus dominicum fuit unitum deitari, et organum animae plenissimae gratias: et deitas radiat super omnem lucem, ut dicitur. Haec est speciolior sole, et super omnem dispositionem stellarum, luci comparata invenitur prior. Quod igitur secundum potestatem deitatis in corpore apparet divino, transfiguratio est in lucem. Et patet, quo illi corpori lux illa connaturalis fuit, sicut et color, sicut in potestate habuit ponendi animan et iterum sumendi eam. Non enim nisi naturale esse potest, quid convenit ei, in quantum erat deitati unitum, et animae cum Deo unitae organum. Unde facta est species vultus eis altera. Et non dicit: alia. Dicit autem ad demulcendum discipulos, et trahendum corda eorum in aeternorum desideriti. Ego diligam eum, et manifestabo ei meipsum. Unde Petrus gloriatur non indoctas fabulas secuti, notam facimus vobis Domini nostri Iesu Christi veritatem et praescientia; scilicet speculatores facti illius magnitudinis. Et tangit in speciali modos dicens [et re facie eius sicut sol] in corpore: in infinitum aurem magis in mente, quam in corpore.  Facies eius sicut sol lucet in virtute sua. Sed contra: sol radiis suis refulgens obcaecat oculos: qualiter ergo sufficere potuerunt. Dicendum, quod confortatum maiori lumine habebant visum. Deinde tangit amictum. Hoc vestimentum potest esse humanitas: quod ego non puto: quia humana facies fuit, quae resplenduit sicut sol. Sed ad literam vestis lucentis nubes alba videtur, ubi splendor occumbere, et in albedinem in circuitu videtur terminari. Significat autem vestis Sanctos.  Vivo ego, dicit Dominus: quia omnibus his velut ornamento vestieris, et circumdabis eos tibi quasi sponsa.  Indutus lumine quasi vestimento. Nix autem est rara, alba et mollis: rara, quia non congelatur, antequam convertatur in aquam, eo quod calidum tenet eam rarem: alba autem propter naturam perspicui aquae, quod est materia eius: mollis autem propter calorem innube conceptum, qui resoluit cogelatum aliquntulum et mollificat. Et rarum quidem significat spiritualitatem: albedo autem innocentiae et castitatis candorem: et mollities mansuetudinem et calor charitatem. Quomodo descendit imber et nix caelo, et illuc ultra non revertitur, sed inebriat terram, et infundit eam, et dat semen ferenti, et panem manducanti: sic erit verbum meum, quod egredietur de ore meo. Vestimenta laba quasi lana munda, et sicut nix, quia lana qualia fullo non potest super terram condida facere. Fullo, inquam, Deus, qui se Sanctis vestis: quia tale lumen Sancti adhuc in terra degentes recipere non possunt Sanctus Albertus Magnus Commentarium in Mattheum, Cap XVII Source: Volumen 9, pdf p213

Behold, the transfiguration. And he describes it in a twofold manner, 1 concerning the Lord and with reference to the witnesses who were on the mount. In Him it also twofold, in the body of the Lord and in His garments. And in the body there is a twofold description, in the common and special modes of His determination. In the common he speaks of the figure that is bounded by quantity, and this figure the Lord does not change. But the figure of the physical body, which has colour and impressions, this is transfigured, when the act of a higher power occurs in it. That is, when in the human body according to its own power the quality of its complexion appears, the color is human. But because the Lord's body was united to the Deity and the state of His soul full of grace: the Deity shines beyond all light, as it is said. 2 And this is a specialty of the sun, that even with all the dispositions of the stars compared to it, it is found to be the first. Therefore according to the power of the Deity in the body, with the Divine appearing, there is a transfiguration into light. And it is revealed that to that body light was connatural, as even its color, just as it had the power of placing down its soul and taking it up again. For not unless it is natural in  it would it happen to it, in as much as the Deity was united to it and  the soul was united with God. Whence Luke says that the appearance of His face was altered to them. 3 And he does not say changed into something else. For he speaks of the impact of it on the disciples and the drawing of their hearts to eternal desire. 'I shall love him and I shall manifest myself to him.' 4 Whence Peter glorifies: 'Following not after uneducated fables, we make known to you the truth and wisdom of our Lord Jesus Christ, as those who have witnessed things of great wonder.' 5 And then Matthew touches in a special manner on something of the body, His face being like the sun, gold being infinitely more in the mind than in the body. 6 So is His face like the sun shining in its strength. But against: 'The sun with its blazing rays  blinds the eyes.' 7 here their eyes were able to see. It should be said, then, that here they were strengthened so that they had sight of the greater light. Then he refers to the garments. This vestment can be understood as the humanity, but I do not think so, because His face was human, which was resplendent as the sun. But the words say that His vestments appeared as white as clouds, when the splendor came, and in a circle of whiteness it seems bounded. And the garment signifies the holy.  'As I live,' says the Lord, 'with all these as an ornament you shall be clothed and they will surround you like a bride's display.' 8  'Clothed as with light as a vestment.' 9 Snow is delicate, white and soft, loose because it does not stick together, until it is turned into water, by which heated it maintains this looseness, white because by nature it is clear like water, which is its matter, soft because of the heat that conceived it in its beginning in clouds, which resolves it from its slight solidity and softens it. And delicacy signifies the spiritual, and whiteness is the colour of the candor of innocence and chastity, and the softness is meekness and the warmth is love. 'How falls the rain and snow from heaven, and there it does not return again, but the earth drinks and it flows into it, and it bears seed, and bread for the eating; so my word shall be, that which goes out from my mouth.' 10 'White vestments like pure wool and like snow.' 11 that wool which no fuller on earth could make whiter. And the fuller, I say, is God, who Himself is clothed with sanctitude, because such light of sanctitude those who live on the earth are yet not able to receive Saint Albert The Great, Commentary On The Gospel of St Matthew, Chap 17 1 Mt 17.1-8 2 Wis 7.29 3 Lk 9.29 4 Jn 14.23 5 cf 2 Pet 1.14-16 6 Mt 17. 2, Apoc 1.16 7 Sirach 43.4 8 Isai 49.18 9 Ps 103.2 10.Isai 55.10-11 11 cf Dan 7.9