“We’re living in a Dark Age of macroeconomics. Remember, what defined the Dark Ages wasn’t the fact that they were primitive — the Bronze Age was primitive, too. What made the Dark Ages dark was the fact that so much knowledge had been lost, that so much known to the Greeks and Romans had been forgotten by the barbarian kingdoms that followed.”

Closing lines
Deadeye Dick (1982)

“Light and Night,” p. 28
The Sun Watches the Sun (1999), Sequence: “Skywalking”

From 1980s onwards, Cosmography (1992)
Context: The dark ages still reign over all humanity, and the depth and persistence of this domination are only now becoming clear.
This Dark Ages prison has no steel bars, chains, or locks. Instead, it is locked by misorientation and built of misinformation. Caught up in a plethora of conditioned reflexes and driven by the human ego, both warden and prisoner attempt meagerly to compete with God. All are intractably skeptical of what they do not understand.
We are powerfully imprisoned in these Dark Ages simply by the terms in which we have been conditioned to think.

" Once by the Pacific http://www.poemhunter.com/poem/once-by-the-pacific-2/" (1928)
General sources
Context: You could not tell, and yet it looked as if
The shore was lucky in being backed by cliff,
The cliff in being backed by continent;
It looked as if a night of dark intent
Was coming, and not only a night, an age.
Someone had better be prepared for rage.
There would be more than ocean-water broken
Before God's last Put out the Light was spoken.

Source: A Hero's Guide to Deadly Dragons

As quoted in "Steve Jobs: The Next Insanely Great Thing" in WIRED magazine (February 1996) http://www.wired.com/wired/archive/4.02/jobs_pr.html
1990s

The Decline and Fall of Practically Everybody (1950), Part III: Strange Bedfellows, Charlemagne

Source: Infinite in All Directions (1988), Ch. 8 : Quick Is Beautiful, p. 135
Context: The technologies which have had the most profound effects on human life are usually simple. A good example of a simple technology with profound historical consequences is hay. Nobody knows who invented hay, the idea of cutting grass in the autumn and storing it in large enough quantities to keep horses and cows alive through the winter. All we know is that the technology of hay was unknown to the Roman Empire but was known to every village of medieval Europe. Like many other crucially important technologies, hay emerged anonymously during the so-called Dark Ages. According to the Hay Theory of History, the invention of hay was the decisive event which moved the center of gravity of urban civilization from the Mediterranean basin to Northern and Western Europe. The Roman Empire did not need hay because in a Mediterranean climate the grass grows well enough in winter for animals to graze. North of the Alps, great cities dependent on horses and oxen for motive power could not exist without hay. So it was hay that allowed populations to grow and civilizations to flourish among the forests of Northern Europe. Hay moved the greatness of Rome to Paris and London, and later to Berlin and Moscow and New York.