Impersonal Verbs

Definition & Preliminary Points
An impersonal verb is one that is not used with a personal subject. In other words, such verbs do not occur in the 1st or 2nd person at all, nor the 3rd plural; in fact, they are used only in the 3rd person singular, and never with any explicit subject (common noun or pronoun). In other words, when translating an impersonal verb literally, the subject will always be "it."
English uses some verbs impersonally, e.g. "it is snowing." It would be silly to say "Herbert is snowing," "Are you snowing today, dear?" or "Gad zooks, the Cardinals really snowed yesterday!" Most verbs used impersonally in English are either so obvious as to require no explanation (as above), or have a rather archaic ring, as
It behooves you to study hard before a math test.


In Latin, there are a few very common verbs used only impersonally but whose meaning corresponds to verbs not so used in English.

The Big 3 Impersonal Verbs in Latin
Here are the three most frequently occuring impersonal verbs in Latin. Note that, being impersonal, these verbs' principal parts are given only in the 3rd person singular (except for the infinitive, of course).
licet, licere, licuit: it is permitted (+ dative)
oportet, oportere, oportuit: it is fitting, it behooves (+ accusative)
placet, placere, placuit: it is pleasing (+ dative)
(all three are 2nd conjugation)

Usage of Impersonal Verbs in Latin, & Literal Translation into English
The usage of these three impersonal verbs is consistent. Each is construed with a person involved, either in the dative or accusative (see above), and with an infinitive of the action that is permitted, fitting, or pleasing. To put it in formulaic fashion:
It is permitted for X to Y. [X = dative of person & Y = infinitive]
It is fitting for X to Y. --or-- It behooves X to Y. [X = accusative of person & Y = infinitive]
It is pleasing to X to Y. [X = dative of person & Y = infinitive]



Converting to Personal Translation in English
Each of these verbs conveys an idea that English can, and indeed may prefer, to express with a personal verb, viz.:
It is permitted for X to Y. = X MAY Y.
It is fitting for X to Y. = X OUGHT to Y.
It is pleasing to X to Y. = X DECIDES to Y.
The pattern is consistent: to convert from impersonal to personal verb, take the dative/accusative of the person and make it into the subject; use the personal verb; retain the infinitive (except with licet, when you lose the "to").
Please note, however, that conversion to a personal verb will not always work. For example:

Notes & a Caveat
Latin has other ways to express the ideas implicit in two of these verbs. oportet can be replaced with debeo, which is used personally; likewise constituo pretty much is synonymous with placet. licet, on the other hand, is unique; there's no easy way around it, if you want to express an action that is permitted.
By the way, be very careful with how "may" is used in English. It may be a subjunctive helping verb, as used (for instance) to translate purpose clauses:
venio ut te videam
I am coming so that I may see you.
But "may" is also used in English as a "modal auxiliary," a special kind of helping verb that indicates something permitted.
You may stay at my house.
tibi licet venire apud me.
One test (not foolproof) to determine the difference: when "may" is a subjunctive helping verb, it is in a subordinate clause.

Wait...There's More!
There are two more points to raise in connection with impersonal verbs.
(1) Certain intransitive regular verbs can be used in what's called "the impersonal passive," an awkward construction utterly foreign to English usage. Hence:
milites fortiter pugnaverunt.
The troops fought bravely.
fortiter pugnatum est.
Literally: "It was fought bravely." Better: "The battle was waged fiercely." or "There was a fierce battle."
Verbs of motion may be similarly used:
tertia hora Romam ventum est.
It was arrived at the third hour at Rome. or Rome was reached at the third hour.
(2) Verbs that take the dative, rather than a direct object, may only be used impersonally in the passive. This is hard to remember, because several straightforward, transitive verbs in English (e.g. "persuade") take the dative in Latin, and cannot be used with personal passive. Thus:
Pompeius was spared.
= It was spared to Pompeius
Pompeio parsum est.
You will be persuaded to leave.
= It will be persuaded to you that you leave. (Remember: "persaude" introduces an indirect command in Latin, but only an infinitive in English.)
tibi persuadebitur ut discedas.


Don't worry too much now about these last two points, which really represent the outer fringes of predictable Latin syntax.