Conclusion:

49. What, then, is the importance of modern science for the argument for the existence of God based on the mutability of the cosmos? By means of exact and detailed research into the macrocosm and the microcosm, it has considerably broadened and deepened the empirical foundation on which this argument rests, and from which it concludes to the existence of an Ens a se, immutable by His very nature.

50. It has, besides, followed the course and the direction of cosmic developments, and, just as it was able to get a glimpse of the term toward which these developments were inexorably leading, so also has it pointed to their beginning in time some five billion years ago. Thus, with that concreteness which is characteristic of physical proofs, it has confirmed the contingency of the universe and also the well-founded deduction as to the epoch when the cosmos came forth from the hands of the Creator.

51. Hence, creation took place in time. Therefore, there is a Creator. Therefore, God exists! Although it is neither explicit nor complete, this is the reply we were awaiting from science, and which the present human generation is awaiting from it. It is a reply which bursts forth from nature and calm consideration of only one aspect of the universe; namely, its mutability. But this is already enough to make the entire human race, which is the peak and the rational expression of both the macrocosm and the microcosm, become conscious of its exalted Maker, realize that it belongs to Him in space and in time and then, falling on its knees before His sovereign majesty, begin to invoke His name: Rerum, Deus, tenax vigor,-Immotus in te permanens, -- Lucis diurnae tempora successibus determinans (Hymn for None).

(A free English translation is: "O God, creation's secret force/Thyself unmoved, yet motion's source/Who from the morn till evening's ray/Through every change dost guide the day.")

52. The knowledge of God as sole Creator, now shared by many modern scientists, is indeed, the extreme limit to which human reason can attain. Nevertheless, as you are well aware, it does not constitute the last frontier of truth. In harmonious cooperation, because all three are instruments of truth, like rays of the same sun, science, philosophy, and, with still greater reason, Revelation, contemplate the substance of this Creator whom science has met along its path unveil His outlines and point out His features.

53. Revelation, above all, makes His presence, so to speak, immediate, vitalizing, and loving, like that presence of which either the simple faithful or the scientist is aware in his inner soul when he recites unhesitatingly the concise terms of the ancient Apostles' Creed: "I believe in God, the Father Almighty, Creator of heaven and earth."

54. Today, after so many centuries which were centuries of civilization because they were centuries of religion, the need is not so much to reveal God for the first time as it is rather to recognize Him as a Father, reverence Him as a lawgiver, and fear Him as a Judge. If they would be saved, the nations must adore the Son, the loving Redeemer of mankind, and bow to the loving inspirations of the Spirit, the fruitful Sanctifier of souls.

55. This persuasion, taking its remote inspiration from science, is crowned by Faith which, being ever more deeply rooted in the consciousness of the people, will truly be able to assure basic progress for the march of civilization.

56. This is a vision of the whole, of the present as of the future, of matter as of the spirit, of time as of eternity, which, as it illuminates the mind, will spare to the men of today a long tempestuous night.

57. It is that Faith which at this moment inspires Us to raise toward Him Whom we have just invoked as Vigor, Immotus, and Pater, a fervent prayer for all His children entrusted to Our care: Largire lumen vespere,-Quo vita nusquam decidat, (Hymn for None)-light for the life of time, light for the life of eternity.