Arafel

As Leto Atreides II the God Emperor disentegrates, his last words to Siona Atreides and Duncan Idaho are, "Do not fear the Ixians, they can make the machines but they can no longer make arafel. I know I was there." After Leto Atreides II dies, Siona explains to Duncan Idaho that arafel is "the cloud-darkness of holy judgment."

Later, Reverend Mother Darwi Odrade discovers the word "Arafel" inscribed in stones of the ruins of Sietch Tabr. It turns out to be a riddle: Arafel = the cloud-darkness of holy judgment at the end of the universe. She then deduced that the Fremen day began with night and following the idea of the darkness of Arafel, she found the Fremen carving of the setting Arrakeen sun. From there, Odrade followed a series of clues until she found a secret chamber containing an undiscovered spice hoard of Leto II and, more importantly, a message from "the Tyrant " to the Bene Gesserit of her own day asking how the sisterhood will meet its end.

Arafel appears to be associated, by implication, with Kralizec "the typhoon struggle;" "the battle at the end of the universe".

Behind the scenes
The word is Hebrew. In modern Hebrew arafel simply means "mist" or "fog." In the Bible however it has a more potent and evocative meaning. The normal Hebrew word for darkness is choshek; the Hebrew word for "cloud" is 'anan. Arafel, however, actually does mean something like "cloud-darkness" as Frank Herbert has Siona explains it in ''God Emperor of Dune. '' Perhaps most significantly, this thick darkness/cloud darkness is quite closely linked with the presence of God.

Arafel occurs 16 times in the Hebrew Bible and in all but one occasion it is directly associated with descriptions of Divine habitation and Divine visitations of the Hebrew God "YHWH" (I've removed the vowels out of respect for Jewish tradition which does not pronounce the "Divine Name"). YHWH is said to shrouded by arafel, "...the Lord has said he will dwell in thick darkness (arafel)" (1 Kings 8:12); "Clouds and thick darkness (arafel) surround him (Psalm 97:2. ) According to the books of Exodus and Deuteronomy, When YHWH appears to the Hebrew people on mount Sinai/Horeb (to affirm the covenant, and reveal the 10 commandments and the rest of the law) he does so amidst fire, thunder and lightning (Ex. 20:19), as well as "darkness, a cloud and arafel (i.e. "thick darkness")" (Deut. 4:11 NRSV). That the arafel is visually impenatrable is implied first by Moses' insistence that because the people saw no visible form of YHWH, they must be careful not to make any graven images (Deut. 5).

The connection of arafel with YHWH's theophany at Sinai and the giving of the law form a natural association with "holy judgment." However, in the Hebrew prophecies, arafel, the "thick darkness"/cloud-darkness," is explicitly associated with warnings and predictions of "holy judgment", . (Deutero?) Isaiah writes, " For darkness shall cover the earth, and thick darkness (arafel) the peoples; but the LORD will arise upon you, and his glory will appear over you" (Isa 60:2 NRS). Jeremiah warns, "Give glory to the LORD your God before he brings darkness... while you look for light, he turns it into gloom and makes it deep darkness (arafel)" (Jer 13:16 NRS). the prophets Zephaniah and Joel predict a future day of judgment called "the day of YHWH." Zephaniah 1:15 "That day will be a day of wrath, a day of distress and anguish, a day of ruin and devastation, a day of darkness and gloom, a day of clouds and thick darkness (arafel)," (Zep 1:15 NRS). Joel words are similar to Zephaniah, "a day of darkness and gloom, a day of clouds and thick darkness (arafel)! Like blackness spread upon the mountains a great and powerful army comes; their like has never been from of old, nor will be again after them in ages to come" (Joe 2:2 NRS).