5 It appears, indeed, that even before this world an order of things existed of which our mind can form an idea, but of which we can say nothing, because it is too lofty a subject for men who are but beginners and are still babes in knowledge. The birth of the world was preceded by a condition of things suitable for the exercise of supernatural powers, outstripping the limits of time, eternal and infinite. The Creator and Demiurge of the universe perfected His works in it, spiritual light for the happiness of all who love the Lord, intellectual and invisible natures, all the orderly arrangement of pure intelligences who are beyond the reach of our mind and of whom we cannot even discover the names. They fill the essence of this invisible world, as Paul teaches us. “For by him were all things created that are in heaven, and that are in earth, visible and invisible whether they be thrones or dominions or principalities or powers” or virtues or hosts of angels or the dignities of archangels. To this world at last it was necessary to add a new world, both a school and training place where the souls of men should be taught and a home for beings destined to be born and to die. Thus was created, of a nature analogous to that of this world and the animals and plants which live thereon, the succession of time, for ever pressing on and passing away and never stopping in its course. Is not this the nature of time, where the past is no more, the future does not exist, and the present escapes before being recognised? And such also is the nature of the creature which lives in time,— condemned to grow or to perish without rest and without certain stability. It is therefore fit that the bodies of animals and plants, obliged to follow a sort of current, and carried away by the motion which leads them to birth or to death, should live in the midst of surroundings whose nature is in accord with beings subject to change. Thus the writer who wisely tells us of the birth of the Universe does not fail to put these words at the head of the narrative. “In the beginning God created;” that is to say, in the beginning of time. Therefore, if he makes the world appear in the beginning, it is not a proof that its birth has preceded that of all other things that were made. He only wishes to tell us that, after the invisible and intellectual world, the visible world, the world of the senses, began to exist.
The first movement is called beginning. “To do right is the beginning of the good way.” Just actions are truly the first steps towards a happy life. Again, we call “beginning” the essential and first part from which a thing proceeds, such as the foundation of a house, the keel of a vessel; it is in this sense that it is said, “The fear of the Lord is the beginning of wisdom,” that is to say that piety is, as it were, the groundwork and foundation of perfection. Art is also the beginning of the works of artists, the skill of Bezaleel began the adornment of the tabernacle. Often even the good which is the final cause is the beginning of actions. Thus the approbation of God is the beginning of almsgiving, and the end laid up for us in the promises the beginning of all virtuous efforts.
Source: Nine Homilies of Hexaemeron (New Advent)