3 In the second place, does the firmament that is called heaven differ from the firmament that God made in the beginning? Are there two heavens? The philosophers, who discuss heaven, would rather lose their tongues than grant this. There is only one heaven, they pretend; and it is of a nature neither to admit of a second, nor of a third, nor of several others. The essence of the celestial body quite complete constitutes its vast unity. Because, they say, every body which has a circular motion is one and finite. And if this body is used in the construction of the first heaven, there will be nothing left for the creation of a second or a third. Here we see what those imagine who put under the Creator's hand uncreated matter; a lie that follows from the first fable. But we ask the Greek sages not to mock us before they are agreed among themselves. Because there are among them some who say there are infinite heavens and worlds. When grave demonstrations shall have upset their foolish system, when the laws of geometry shall have established that, according to the nature of heaven, it is impossible that there should be two, we shall only laugh the more at this elaborate scientific trifling. These learned men see not merely one bubble but several bubbles formed by the same cause, and they doubt the power of creative wisdom to bring several heavens into being! We find, however, if we raise our eyes towards the omnipotence of God, that the strength and grandeur of the heavens differ from the drops of water bubbling on the surface of a fountain. How ridiculous, then, is their argument of impossibility! As for myself, far from not believing in a second, I seek for the third whereon the blessed Paul was found worthy to gaze. And does not the Psalmist in saying “heaven of heavens” give us an idea of their plurality? Is the plurality of heaven stranger than the seven circles through which nearly all the philosophers agree that the seven planets pass—circles which they represent to us as placed in connection with each other like casks fitting the one into the other? These circles, they say, carried away in a direction contrary to that of the world, and striking the æther, make sweet and harmonious sounds, unequalled by the sweetest melody. And if we ask them for the witness of the senses, what do they say? That we, accustomed to this noise from our birth, on account of hearing it always, have lost the sense of it; like men in smithies with their ears incessantly dinned. If I refuted this ingenious frivolity, the untruth of which is evident from the first word, it would seem as though I did not know the value of time, and mistrusted the intelligence of such an audience.
But let me leave the vanity of outsiders to those who are without, and return to the theme proper to the Church. If we believe some of those who have preceded us, we have not here the creation of a new heaven, but a new account of the first. The reason they give is, that the earlier narrative briefly described the creation of heaven and earth; while here scripture relates in greater detail the manner in which each was created. I, however, since Scripture gives to this second heaven another name and its own function, maintain that it is different from the heaven which was made at the beginning; that it is of a stronger nature and of a special use to the universe.
Source: Nine Homilies of Hexaemeron (New Advent)