We are a couple in our mid seventies. We want to remain relevant. Our company tag-line is "Feeding the urban population within urban boundaries" Our way of doing this is to use the light spectrum effectively for growing food in covered environments. Lots of highly sophisticated electronics. Our friends (and enemies) wonder why we care, when our lives are at the pointy ends. Our response is that we do it because we can, and we think we should. We will not see much of the results.

So we would like to have the motto "he who can, must" or similar in Latin. One of us is a word-nerd; the other not so much.

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    Thank you all so much. I loved my (very) long ago latin studies, and your talking about these delicate uses of words made me very happy. Victoria.
    – Victoria
    Commented Oct 13, 2022 at 6:33

2 Answers 2


I have three suggestions:

  1. Potentis est facere.
  1. Qui potest, debet.
  1. Si potes, fac.

The first one is "it is of the able to do", which in more fluent English would be "it is the duty of the able one to do". This is singular; if you want several able ones, switch the first word to potentium.

The second one is more straightforward, "[he] who can, must". The word debere has many meanings, e.g. "owe money" in addition to "must", but ambiguity is common in a concise motto.

The third option is a direct order: "If you can, do." It really reads as an order rather than a description, so it feels different and quite strong.

I find the first one to be of better style, but it's a matter of taste. Let me know if you have any questions on details, nuances, or options.

  • How about: Cui faciendi potestas, eidem faciendum est.
    – Patricius
    Commented Oct 10, 2022 at 10:31
  • @Patricius That's certainly possible, but I aimed at something shorter. Can you write that up as a separate answer?
    – Joonas Ilmavirta
    Commented Oct 10, 2022 at 13:04
  • The problem with the second option is English, where it sounds like it should mean “Whoever protests owes money”. How about qui potest, faciat? The subjunctive is not quite right (it covers potential action, but not moral duty, I don’t think), but it avoids the loaded word debit. Commented Oct 10, 2022 at 16:50
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    @MichaelLorton The Latin debere means a number of things, including both "must" and "owe money". Ambiguity is pretty much inevitable in a concise motto. You could use the third person future imperative: qui potest, facito. I'll add a third option to my answer and a comment on ambiguity.
    – Joonas Ilmavirta
    Commented Oct 10, 2022 at 19:52

I would suggest:

Cui faciendi potestas, eidem faciendum est.

Which means:

"He who has the power to do it is the one who must do it," or "The one who is able do it is the very one who's got to do it."

This is much less pithy than “He who can, must,” but I think more precise—perhaps a little too precise for your purposes.

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