Now these two things, their light and their movements, were all the facts concerning the stars which mediæval astronomers could observe; and the movements were thought to be in circles and inconceivably rapid. Motion in circles, and especially the movement of rotation on an axis, remaining in the same place, had been said by Aristotle to be the most noble form of motion, and the fittest for celestial bodies. Therefore, when Dante represents the redeemed and the angels as expressing their bliss by radiance and marvellously rapid motion in circles, he makes them resemble the heavenly spheres and stars among which they manifest themselves to him. The motions are directly compared with those of stars in the passage already quoted:— “Poi, sì cantando, quegli ardenti soli Si fur girati intorno a noi tre volte, Come stelle vicine ai fermi poli.”[316] ------------------------------------------------------------------------ [316] “As soon as singing thus those burning Suns Had round about us whirled themselves three times, Like unto stars neighbouring the steadfast poles.” _Par._ x. 76-78. (_Longfellow_). ------------------------------------------------------------------------ Remembering this significance of circular motion we shall feel a little less strange the similes of a mill and a top applied to the spirits of Paradise.[317] A third way in which the spirits express their joy is by the sweetness of their song,[318] and here also they resemble the heavenly bodies, which make sweet music as they circle. This doctrine of Pythagoras was very popular throughout the Middle Ages. ------------------------------------------------------------------------ [317] _Par._ xxi. 80, 81; xii. 3; xviii. 41, 42. [318] _Par._ xxiv. 22-24, x. 73, and many others. ------------------------------------------------------------------------ 4. THE GALAXY. The Galaxy or Milky Way is twice referred to in the _Divine Comedy_. In _Inf._ xvii. 106-108, it is in connection with the myth of Phaeton, who being allowed by his father Jove to drive the chariot of the sun for one day, lost control of his chargers, and going all astray, burned the sky in a part which still shows signs of this catastrophe, _i.e._ the Milky Way. “Quando Fetòn abbandonò li freni, Per che il ciel, come pare ancor, si cosse.”[319] ------------------------------------------------------------------------ [319] “What time abandoned Phaëton the reins, Whereby the heavens, as still appears, were scorched.” _Inf._ xvii. 107-108. (_Longfellow_). ------------------------------------------------------------------------