What are good Latin equivalents to the Finnish concept sisu?

Question

I am not Finnish, but having spent most of my adult life in one of the counties bordering to Finland, the word sisu has not escaped me, though a proper understanding of what it means requires a cultural insight which I probably do not possess. Store norske leksikon explains sisu as such:

Sisu er finsk og betyr utholdenhet, seig kraft, kamplyst, både legemlig og sjelelig.

Faktaboks
UTTALE sˈiːsu
ETYMOLOGI fra finsk sisu, egentlig ‘det indre’

Sisu is Finnish and means perseverance; raw, prolonged power; will to fight, both corporeal and spiritual.

Etymology: from Finnish sisu, original meaning ‘the inner’

What are good ways to translate sisu to Latin? I am especially looking for attested, conceptualised forms from any period. Finnish Latinists are especially encouraged to answer, as they presumably possess the cultural background to fully conceptualise what is meant by the term.

Answer 1

I thought a Finnish-Latin dictionary should know. I do not have access to printed Finnish-Latin reference works, but did find two online dictionaries:

• Sanakirja.org has a Finnish-Latin dictionary function, but it does not know the word ”sisu”.
• IlmainenSanakirja.fi knows it and suggests: firmitas and voluntas. (I cannot vouch for the quality of this website, but since it's the sort of dictionary that offers simple clickable one-word answers, it's probably not very good.)

Of these two suggestions, I think firmitas is the better fit. Lewis & Short translate it as:

firmness, durability, strength [⋯] steadfastness, stability, endurance, constancy, power

It's classical and not too rare, too.

Voluntas, on the other hand, may correspond to some aspect of ”sisu” in Finnish, but has little to do with the mystical qualities of the word that have been highlighted here, I think.

Answer 2

I'm still not 100% I know precisely what sisu is, nor am I still sure I know what kind of answer you're looking for. But generally I see two divergent paths of options: one for encapsulating "national character" and one an etic perspective of what sisu looks like.

For the latter, the two words that immediately sprang to mind are perseverantia, a type of steadfastness under pressure, and obdurare, of similar meaning. The latter's nominal form obduratio is very rare and late, so if you're looking strictly for a noun, the former might be a better choice. I like the latter though since it shows up frequently in good authors and famous passages, such as Catullus' perfer et obdura. Obduro also shows up more frequently in the context of emotional hardening, while in war contexts "holding out" is more often described with persevero.

But neither word really holds an elevated place as a national characteristic. For that, I wonder if a more general virtus might not be appropriate. Its most fundamental meaning is of course tied to vir, but it not only means "manliness," but "good character, strength, courage, mental fortitude, value, and even stubborness, "the sum of all the corporeal or mental excellences of man" (Lewis and Short).

I'm not sure this is a good translation or particularly Latin equivalent to sisu, but I think it makes for a good Roman equivalent, that is, if I understand this word correctly.

Answer 3

The Catholic and Thomistic concept of fortitude has some wide overlap: both concepts involve inner strength, presence of mind, endurance, determination. Hence eccl. Latin fortitudo would do.

That said, there are some important differences. I talked to a friend of mine* that happens to be fluent in Finnish and familiar with this concept of fortitude. (Please, Joonas, feel free to correct.) According to him:

• Sisu makes emphasis in extremely adverse circumstances
• Sisu is somewhat innate (if I got it right)
• Sisu depends strongly on oneself
• fortitudo has also to do with acting consistently with one's way of thinking
• fortitudo is a virtue (as opposed to a vice), that is, a habit that is acquired through repetition of good actions.

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As a conclusion, as Joonas said in the comments the best choice will depend on context, and if you want to be precise in the meaning, you would probably need a few more words to convey the whole meaning. (How about something like nata fortitudo in extremis apparens?)

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(*) My friend gave me two definitions that could help:

1. 

2. "Sisu is more than just a word; it is very much embodied as part of Finland’s national character. On the one hand, it is a mystical almost magical force, thing, concept or entity that occupies the core of Finnish spirit, values and culture; while on the other, it is something deeply personal that as the exists in the heart of Finns in terms of who they are as individuals and who they are as a people." (source)