Paradise began as a Persian word for a walled royal park
Before it meant heaven, paradise meant a wall around a garden. The Old Iranian term described enclosed estates of Persian kings; Greeks used it for animal parks, Hebrew for orchards, and translators of Genesis for Eden. One word travelled from landscaping to the afterlife, and in modern Persian it can still mean a vegetable patch.
The root combines pairi-, around, with a verb for building a wall, both traceable to Proto-Indo-European. By the 6th or 5th century BCE Assyrian had borrowed it as pardesu, meaning domain, and it came to name the great walled gardens of the first Persian Empire. The Athenian Xenophon, writing early in the 4th century BCE, used parádeisos for a hunting park, and Aramaic speakers used it for a royal park.
In Hebrew, pardes shows up only after the exile of 538 BCE, three times, in the Song of Songs, Ecclesiastes and Nehemiah, always as a park or orchard. The Septuagint, the Greek translation made between the 3rd and 1st centuries BCE, used parádeisos for the garden of Genesis, and Jerome's Latin Vulgate followed, adding pleasure because Eden itself comes from a root meaning delight. The Quran's firdaws continues the same word.
Meaning then shifted from a lost garden to a destination. Second Temple Judaism linked paradise with Eden restored and eventually with heaven, and rabbis distinguished a lush lower Garden of Eden from a celestial upper one for righteous souls, Jewish and non-Jewish. The Zohar turned the letters of pardes into an acronym for four levels of reading the Torah, from literal to mystical. Irenaeus in the 2nd century and later Origen kept paradise separate from heaven, Origen calling it a school where righteous souls prepare to rise.
One comma may hinge on this debate. In Luke 23:43 Jesus tells a man crucified beside him that he will be with him in paradise, but early manuscripts disagree on whether today belongs with I tell you or with the promise itself; Codex Vaticanus has a pause mark between the two readings. Other cultures pictured similar places: the Egyptian reed fields of Aaru, the Celtic Mag Mell, the Greek Elysian fields and the Zoroastrian House of Song. Milton's Paradise Lost gave the idea its most famous English treatment.
Source: Paradise