The agent of a passive construction is in ablative, and human agents also come with the preposition a/ab. For example, Marcus a Gnaeo occisus est but Marcus sica occisus est. But which agents should be considered human?

Many cases are clear, but there are also less obvious situations. For example, are gods, dolls, anthropomorphic robots and pets with human-like status human? My Latin grammar gives the example A Deo mundus creatus est, implying that the Christian god can be viewed as human — without implying that it would always be viewed so.

Can you give some guidelines for choosing which agents to consider human and which ones non-human? I would prefer the guidelines to be backed by classical usage or a reliable grammar book.


2 Answers 2


Ovid's Remédia Amórés 422 suggests that your grammar is mistaken and that non-humans with agency can be considered agents:

Á cane nón mágnó sæpe tenétur aper.

Cicero's Dé Officiís 1.68 suggests that, at least metaphorically, emotions can be considered agents:

Nón est autem cónsentáneum, quí metú non frangátur, eum frangí cupiditáte, nec quí invictum sé á labóre præstiterit, vincí á voluptáte.

What I take from these examples, along with others, such as this from Livy III.37, which suggest that humans can be instruments

Et decemvirí, quí prímó tribuniciós hominés, quia id populáre habebátur, circum sé ostentáverant plebí, patriciís iuvenibus sæpserant latera.

—is that, pace nineteenth-century grammarians, we are permitted to and indeed must decide for ourselves, when determining what construction to use, whether any given noun is functioning as an agent or an instrument—that is, whether it is exercising its will (agent; use the preposition) or being used by something else that is exercising its will (instrument; omit the preposition).

  • 2
    Interesting. Do you happen to know if there is any difference in tone between using a preposition and using a plain ablative? Perhaps a preposition emphasizes control of the situation as opposed to being just a reason or a tool?
    – Joonas Ilmavirta
    May 7, 2016 at 0:21
  • 4
    I think that's exactly it. The preposition emphasizes an exercise of will. The dog desires to hold the boar, and the villainous pleasure desires to break a man. Similarly, though one presumes that when the actual event occurred the young patricians had a say in where they stood, Livy is emphasizing their use as tools by the decemvirs: in this sentence their only existence is as physical objects, not as actors. May 7, 2016 at 0:45
  • It all makes sense that way, and it also explains why the preposition usually comes with humans but usually not with inanimate objects. Could you add that to your answer in some form?
    – Joonas Ilmavirta
    May 7, 2016 at 0:49
  • Dicto audiens sum. May 7, 2016 at 0:52
  • It's somewhat ironic that in Spanish, it is the accusative that takes a preposition (a, descended from Latin ad) only with animate objects, kind of exactly "mirror-reversing" what happens in Latin with the (arguably "opposite" case) ablative, the agent/instrument, and a/ab. Aug 13, 2023 at 13:12

I think there is a semantic difference between "a Gnaeo" for the agent and "sica" for the instrument. The agent will be expressed in this way only in a passive sentence, but the ablative of instrument can be used also in an active sentence (Marcum sica occidit). The agent is normally animate. Note that there is a difference between "animate" (=humans, gods, animals), "rational" (=humans and gods, but not animals) and "human".

  • My grammar specifically mentions "human", not "animate", but it could be an error. (I double checked my book and it indeed says so.) It also lists agent as a special case of instrumental ablative, so the border between an instrument and an inanimate agent becomes fussy (as it semantically is).
    – Joonas Ilmavirta
    May 6, 2016 at 11:37

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