Quatrain 34

The Revelations of Devout and Learn'd
Who rose before us, and as Prophets burn'd,
Are all but Stories, which, awoke from Sleep,
They told their comrades, and to Sleep return'd.

FitzGerald, Stanza LXV, 4th ed.

Heron-Allen (99) cites C 127 as the quatrain-source for FitzGerald, also found in Dashti (3), Hedaayat (12) and Forughi-Ghani (54):

آنان که محیط فضل و  آداب شدند
از جمع کمال شمع اصحاب شدند
ره زین شب تارنک نبردند برون
گفتند فسانه ‌‌ٔ* و در خواب شدند

(* in a more modern text you would see فسانه‌ای)

aanaan ke mohit-e fazl o aadaab shodand
az jam`e kamaal sham`e ashaab shodand
rah zin shab-e taarik nabordand berun
goftand fasaanei o dar khaab shodand

The saint and seer profound in wit and lore,
Who torch of knowledge 'mongst the sages bore,
Out of darksome night could find no way;
Some tales they told, then went to sleep e'ermore.

Saidi, quatrain 57

Taking a stab at the literal, Heron-Allen, 99:

Those who have become oceans of excellence and cultivation,
And from the collection of their perfections have become lights of their fellows,
Have not made a road out of this dark night,
They have told a fable and have gone to sleep.

They, who, renowned for lore and power of brain,
As "Guiding Lights" men's homage did obtain,
Not even they emerged from this dark night,
But told their dreams, and fell asleep again!

Whinfield, quatrain 209

This is a familiar theme, the mystery of existence and the pundits who delve into the mystery, into the sea of existence, بحر وجود - see Quatrain 8. 

Note that I referred to the source-quatrain for FG in my Quatrain 20, and it may be useful for site viewers to have a look at 20 for the befuddlements of "pundits and problem solvers."

Compare also this quatrain, which is my Quatrain 46:

اجرام که ساکنان این ایوانند
اسباب تردد خردمندانند
هان تا سررشتۀ خرد گم نکنی
کانان که مدبرند سرگردانند 

Dashti, quatrain 7, p, 245

ajraam ke saakenaan-e in ayvaanand
asbaab-e taraddod-e kheradmandaanand
haan taa sar-e reshte-ye kherad gom nakoni
kaanaan ke modabberand sar gardaanand

The heavenly spheres which in this domain reside,
Have bewildered the wise, thinking far and wide;
Behold and don't lose the trail of wisdom,
For the price of wisdom is to reel to every side.

Aminrazavi, 188

Consider also that the powerful and mighty, the Bahrams and Jamshids, for all their prowess and learning, could not survive any more than these arbiters of excellence.  And FitzGerald may be commended for following his source material!