ÉRSÉKE - 'ere-sake': cause of an effect

depictions with causes and consequences of marriage, by Daniel Nikolaus Chodowiecki, 1788 (source, source)

ÉRSÉKE, plural. ÉRSÉKA
'cause', as in 'cause and effect': reason for something taking place or for something being so; rational explanation.

Some modern cognates:
oorzaak - Dutch
oorsaak - Afrikaans
oarsaak - Frisian
Ursache - German
årsagen - Danish
årsaken - Norse
orsaken - Swedish
orsökin - Icelandic

Compound word of:

ÉR (superlative: ÉROST)
ere (first) - English
eer (eerst) - Dutch
ehe (erst) - German
etc.

and:

SÉK(E), plur. SÉKA/-UM
sake (case, thing, matter) - English
zaak - Dutch
Sache - German
etc.

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Some Oldfrisian dictionaries seem to have limited understanding of the word:

Koebler: êrseke 2, afries., F.: nhd. alte Feinschaft; ne. animosity

Hettema 1832

Richthofen 1840

The same applies to the Dutch etymology site:

Derivation with 'oor-' with the noun 'zaak' (case) in the sense of ‘dispute, strife, lawsuit’. The original meaning is "ground for contention and accusation, cause for hostile action," in accordance with the oldest sense of 'case'.

Fragments in Codex Oera Linda:

1b. Adela’s Advice [002/10]
HJA HÀVON ÍNES ÔTHER.IS FRYDOM BINIMEN ÀND THÀT IS ÉRSÉKE THÀT HJA HJARA AJN VRLÉREN HÀWE.
They took the freedom of another and that is why they have lost their own freedom.

9c. Kelta and the Gools [068/10]
THRVCH AL THESSA ÉRSÉKA KVN HJRA FOLK NAVT NI LÉRA.
As a result of all this, her folk could not learn.

12. Adelbrost: Intrigues and Division [087/25]
SJVGUN MÔNATHA ÀFTER WERTH.ER EN MÉNA ACHT BILIDSEN ÀND WEL TO GRÉNEGÁ UT ÉRSÉKE THAT ANNA SAXANNA MARKA PÁLTH.
After seven months, an assembly was planned in Greanega, since it is close to the Saxonmarks.

13b. A Treacherous Maid [091/20]
HJU HÉDE IMMERTHE WÉNICH WÉST THÀT HJU MODER SKOLDE WERTHA UT ÉRSÉKE THÀT HJU HÍR VPPER BURCH SAT HWANA MÉST ALLE MODERUM KÉREN WÉRON.
She had always hoped to become Folksmother because she sat in the burg here, where most elected mothers had been burgmaids.

18. Rika: Title Theft [189/10]
THACH THÀT WÉTHATH JY ALLE. THÀT HY WARTH AL.FÉDER HÉTEN. UT ÉRSÉKE THÀT ALLES INUT IM WARTH ÀND WAXTH TO FÉDING SINRA SKEPSELA.
But this you all know, that he is called ‘All-feeder’, because everything comes from and grows out of him, so that his creations may be fed.

Fragments with SÉK(-E/-A/-UM); in many cases the translation is paraphrased, not literal:

SEND MY FÉLO SÉKA BÁR WRDEN
many things have been revealed to me
IS THJU SÉK VR ÉNE STÁTE
If the affair concerns only one district
BY ALLE SÉKUM
Upon all matters
ÉNNE RJUCHTLIKA SÉKE
any judicial question
FINDATH HJU THJU SÉKE TVIVELIK
she deems the case doubtful
THA MÉNA SÉKA
the common cause
NETLIKA SÉKA
Useful precedents
VR ENZE SÉKA THA VR LÁND
over some cause or piece of land
SÉKA. STRIDANDE WITH VSA FRYA SÉDUM
matters that are in conflict with our Frya morals
VMBE AN MÉNA SÉKA TO NOMANDE
for mundane use
ALLE SÉKUM BINN ÁTHÉNJA
all cases in Athenia
THÁS ÀRGE SÉKE
his cruel plot
EN SÉKE THÉR FÉLON STÁTHA TROF
a case concerning several districts
AL THISSA SÉKA HETH HJRA BODA SELVA BILIAD.
All this was confessed by her messenger himself.
THISSA SÉKA MOTON KLÁR ÀND BÁR MÁKAD WRDA
These facts must be made clear and manifest
THA ÔRA SÉKA FINTH MAN VPPA ÔRA THRJA.
The remaining three walls hold other texts.
NÉN LJUCHT NER KLÁRHÉD IN THJUSE SÉKE
no light or clarity in this matter
KESTLIKA SÉKUM
precious things
MEN THA JONGA FÁMNA SPÔND.ER MITH GOLDNE FIN’GRUM AN SINA SÉK.
but with golden fingers he wove the young maidens into his project.
SVMLIKA SÉKA THÉR MIN TÁT ALLÉNA JELDE
some parts which concern only my father
THÉRVMBE NE THURVATH SE FAR HJARA SÉK NIT ÔPENTLIK UT NI KVMA.
Therefore, the people dare not openly declare their creed.
MITH HWAMHIS HELPE HI ALLE SÉKUM ÁSKTE
with whose help he pushed through all policies

= = = possibly related: SÉKUR: sure, secure; (BI)SÉKA(NE): seek; SÉKROPS (name); NÉDSÉKTE: necessitated (Dutch: 'noodzaakte')

More about ÉR in a following post.