Quatrain 36

The Moving Finger writes; and having writ,
Moves on: nor all your Piety nor Wit
Shall lure it back to cancel half a Line,
Nor all your Tears wash out a Word of it.

FitzGerald, Stanza LXXI, 4th ed.

Heron-Allen, 105, identifies this quatrain below, Bodleain Ouseley, 31, as the "origin" of FitzGerald's stanza above:

زین پیش نشان بودنیها بوده است
پیوسته قلم ز نیک و بد ناسوده است 
در روز ازل هرآنچه بایست بداد
غم خوردن و کوشیدنِ ما بیهوده است

zin pish neshaan-e budanihaa budast
peyvaste qalam ze nik o bad naasudast
dar ruz-e azal har aanche baayest bedaad
gham khordan o kushidan-e maa bihudast

From the beginning was written what shall be;
Unhaltingly the Pen (writes) and is heedless of good and bad;
On the First Day He appointed everything that must be--
Our grief and efforts are in vain.

Heron-Allen, 107, from Ouseley 31 and Calcutta 87 -- H-A notes that in the Calcutta MS the first line reads بر لوح, bar lowh, "upon the tablet."

What was to be was written long ago,
the restless pen spared nothing good or bad;
first day it gave us the rules of life,
our pouting, trying harder ... a waste of time.

Arberry, Romance ... , 224-225 also refers to this quatrain  and its influence on the FitzGerald stanza above as well as on another stanza we will come to later in this page, namely, Stanza LXXIII (LIII in the first edition).  But Arberry here credits Bodleian/Ouseley 54 as the "chief source" for FitzGerald's "The moving Finger writes ..."  Here's the quatrain:

از رفته قلم هیچ دگر‌گون نشود
وز خوردن غم بجز جگرخون نشود
گر در همه عمر خویش خونابه خوری
یک قطره از آن که هست افزون نشود

az rafte qalam hich degargun nashavad
vaz khordan-e gham bejoz jegarkhun nashavad
gar dar hame omr-e khish khunaabe khori
yek qatre az aan hast afzun nashavad

(Note the rather nice word-play, pun or paronomasia (tajnis/تجنیس , "making similar") in the italicized romanization and in the Persian itself, unitalicized)

Nothing becomes different from what the the Pen has once written,
and only a broken heart from nursing grief;
though all you life you swallow tears of blood
not one drop will be added to the existing score.

Arberry, 224

& also note:

از رفته قلم هیچ دگرگون نشود
یک ذره  از آنچه هست افزون نشود
هان تا جگر خویش بغم خون نکنی
کز خوردن غم بجز جگرخون نشود

Govinda Tirtha, Nectar of Grace, VI.12
(from a MS source apparently different from O.54)

az rafte qalam hich degargun nashavad
yek zarre az aanche hast afzun nashavad
haan taa jegar-e khish begham khun nakoni
kaz khordan-e gham bejoz jegarkhun nashavad

The Fate will not correct what once she writes,
And more than what is doled no grain alights;
Beware of bleeding heart with sordid cares,
For cares will cast thy heart in wretched plights.

Tirtha

Two Latin sketches for (our introductory) Stanza LXXI and for (the "promised") LXXIII to follow:

Unocuique* Lex suprema Calamo currente transit
[...] irrevocandum mansit:
Quod si toto Lachrymarum  [...] lavares
Minimum Indicium [...] non obliterares.
*FitzGerald meant to write unicuique -- the sketch of course is unfinished

The supreme Dictate -- the pen moves on -- applies to everyone
[...] has remained irrevocable
But if you were to bathe it in all your tears
you would not erase the tiniest jot of it.

Indoles uniuscunque praedispos[ita] ante natum
Calamusque currens cuique proprium praescripsit Fatum:
Quod postremus indicabit Dies indicavit primus:
Quare me Peccati pudet quod peccari designatum?

The way and nature of each person was determined before birth
and the pen moves on as it orders the fate determined for each:
What the final day reveals will be what the first day marked down:
Why is my sin shaming me, sin that was my fate?

FitzGerald, Stanza LXXIII:
With Earth's first Clay They did the Last Man knead.
And there of the Last Harvest sow'd the Seed:
And the first Morning of Creation wrote
What the last Dawn of Reckoning shall read.

In my opinion, it is likely that FitzGerald used both Bodleian/Ouseley quatrains (31 and 54) for the two stanzas in this post namely, "The Moving Finger writes..." and "With Earth's first Clay..." I would not favor the influence of one over the other. I also believe that Stanza LXXIII, "With Earth's first Clay ..." although similarly influenced, shows, especially in the first two lines, some of FitzGerald's inventiveness.  What FitzGerald failed to incorporate into his stanzas from Ouseley 54, is the broken heart and the swallowing of tears of blood. And he ignores the observation (see also our Quatrain 10) that nothing but injury can come from nursing grief.

The fourth line of the second Latin sketch: Quare me Peccati pudet quod peccari designatum, "Why is my sin shaming me ...sin that was my fate?" has no bearing on these stanzas but rather anticipates Stanza LXXX (if not the two stanzas before that), Thou wilt not with Predestin'd Evil round/Enmesh, and then impute my Fall to Sin!. LXXX, however, is thought, and rightly so, to have had its origin in Bodleian/Ouseley 148 (Arberry, Romance ... 227). 

There is no official vote on the popularity of FitzGerald's stanzas, but I would wager that "The Moving Finger writes..." and "A Book of Verses underneath the Bough" -- our Stanza 22 -- would be at the top of the list.