Father John Eusebius Nieremberg (Juan Eusebio Nieremberg), (Madrid, Spain, 1595-1658) was a Jesuit priest, theologian and mystic. Man was created by God to praise Him, make Him reverence and serve Him, and thereby save his soul; and the other things on the face of the earth are created for man, and to help him in the pursuit of the purpose for which he was created. Hence it follows that man must use things as much as they help him to his purpose, and so much he must remove them as they prevent him from doing it. Therefore, this “difference” between the temporal and the eternal is related to the purpose of man’s life. Nieremberg intends in this work that the reader internalizes this “difference” in a vital and existential way, deepening the thought of eternal life, whether in heaven or in hell. The “things on the face of the earth”, the temporal, are means that must be “used” to reach the purpose, or happy eternity with God, the Creator. In the prophetic book of Revelation, chapter 10, 1-7 we are told of the end of time: “I saw another mighty angel descending from heaven in a cloud; he had a rainbow over his head, and his face shone like the sun, and his feet like pillars of fire, and in his hands he had a little book open. Putting his right foot on the sea and his left on the ground he cried out with a mighty voice like a roaring lion … Then the angel who was on the sea and on the earth raised his right hand to heaven and swore by the one who lives forever and ever, which created the heavens and all that is in it, the earth and all that is in it, the sea and all that it contains, there shall be no more delay.” That is that there will be no more time for anyone. At that moment, time will end and eternity will follow infinite because it will never end. “Great thought” St. Augustine called the thought of eternity, which can make saints out of the greatest sinners. And St. John of Avila affirmed that “he who believes in eternity and does not become holy deserves to be locked up in a house of madmen”