In English we sometimes use the word "once" to indicate a logical precondition born of experience. For example, "once you know you to ride a bike, you never forget" or "once you meet her, you will understand" or "once you have tried an electric mower, you will never go to back to gasoline". I am wondering how to express this idea in Latin. Of course, we can rewrite it as "if": "if you know how to ride a bike, you will never forget" but that is not exactly the same idea.

What makes the usage tricky is that it is both a logical and a temporal precondition at the same time.

The word that comes to mind immediately is quondam, once it happened that..., but I am not sure this is the right word because it does not imply that something is a precondition for something else.

I notice that in Cicero's Rhetorica ad Herennium there is the following expression: quod poteris existimare utilitate cognita (once you know its usefulness, you will be able to appreciate this [advice]), so we can potentially view the ablative absolute as serving the purpose wanted, but maybe we need more than this?

In the Metamorphoses, there is a sentence where the author spells it out with usu venerit: Sed cui hoc usu venerit, numquam postea comitiali morbo adtemptatur... (But once this has happened to someone, they never again are afflicted by epilepsy...). So, I suppose that is an approach.

Maybe there is an adverb that captures the idea?

2 Answers 2


The English word once as used here basically means the same thing as after. Most first year Latin textbooks give an entire section on how to express temporal subordinate phrases.

To which I will add that after can often be expressed by the perfect participle in Latin, especially in pithy sayings.

"Once you learn how to ride a bike, you will never forget" can become scitus birota vehendi, numquam oblivisceris.

"Once you meet her, you will understand", Ea cognita, intelleges.

"Once you have tried an electric mower, you will never go to back to gasoline", Herbisectro electronico adhibito, ad benzinecum nunquam regredieris.

  • "After" does not imply a logical relationship, only a temporal one. Commented Nov 3, 2022 at 7:02
  • I think an ablative absolute with a perfect participle is a great fit. It has both temporal and causal flavours, which works well here.
    – Joonas Ilmavirta
    Commented Nov 3, 2022 at 13:19

After thinking about this some, I first thought maybe semel with the ablative absolute, but the problem with that is that semel just means once, but we could be describing an experience that had continuing action in the past.

Then on further research I noticed the following passage in Ausonius: igitur cui hic ludus noster non placet, ne legerit, aut cum legerit, obliviscatur, aut non oblitus ignoscat. So this would suggest using cum with the perfect. So, we might have:

Cum novisti birotam agere, numquam oblivisceris.

Note the use of the perfect here. (For example, "nosti mores mulierum" means "you know how women are" even though it literally means "you knew the ways of women"). So, the perfect is used to indicate accomplishment, and cum in this context indicates both the logical and temporal precondition.

So, this might be a solution, but there may be better.

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