[noun in nom.] + [linking verb] + [adj. in nom.]

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amicius modifies nihil in case, number, and gender.  pares modifies the "we" of sumus, also in case, number, and gender.

NOTE:  Nominative adjectives used as predicates are often called predicate adjectives.

[noun in acc.] + [linking verb] + [adj. in acc.]

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In the above examples, studiosum and confirmatum are accusative in order to modify Lentulum and te, respectively.  Both Lentulum and te are accusative because they are the objects of habemus and videro, respectively.

On the other hand, they are accusative because habemus and videro set up indirect statements, with esse understood in each case.

If this were direct statement, we would have something like this: si Lentulus est tam studiosus and si tu confirmatus es.  The addition of habemus and videro mandates a change from predicate nominative to predicate accusative.

NOTE:  If the subject is nominative, the predicate must also be nominative;  likewise for accusative subjects.  There can be no mixing and matching of cases, no nominative subjects with  predicate accusatives, or vice versa.

[pres. stem of verb] + [-nd-] + [1st or 2nd decl. adj. ending]

Example:  amare, to love = ama + nd + a (nom. sing. fem.)
 
 

amanda, she who must be loved.

As you can see, there are as many gerundives as there are cases, numbers, and genders.  Since gerundives can be masculine or feminine or plural, they are easily identified as adjectives.  Conversely, if you see what looks to be a gerundive all by itself, and in the neuter singular, you are probably looking at a gerund, which is a verbal noun.

Gerund or gerundive?, that is the question.  In theory,  the  following sentence, which utilizes the gerund, makes grammatical sense.

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amando governs libros as its object.  In practice, however, such constructions are rare.  Here is what Cicero would have written, using the gerundive:

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In this sentence, libros becomes libris.  That is, what was formerly a direct object is put into the case of our theoretical gerund (amando), an ablative of means.  The gerund is then replaced by a gerundive, amandis, which modifies libris in case, number, and gender.  This is the noun + gerundive construction, and it is favored over gerund + noun.

NOTE:  The above translation is very literal.  For the sake of convenience, if not sanity, we would translate as, She lives by means of loving books.  In other words, we translate as if we had gerund + noun.

Here is a noun + gerundive sentence from our reading:

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The key words are de nuntio remittendo, lit. concerning the decree to be remitted (filed).  This phrase replaces de remittendo nuntium, gerund + noun, where remittendo would take nuntium as a direct object.

The reason why nuntio remittendo is identifiable as noun + gerundive is that nuntio is clearly ablative, which means that remittendo must be an adjective.

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The last two sentences use ad + the gerundive to express purpose.  Compare this construction with purpose clauses and relative clauses of purpose.

[nom. noun] + [linking verb] + [gerundive predicate] + [dat. agent]

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The passive periphrastic, which expresses duty or obligation, is nothing more than the gerundive functioning as a predicate nominative after a linking verb.

In sentences 2 and 3, dandum modifies ius in case, number, and gender (nom. sing. neut.), while faciendum does the same for quid.  Usually the linking verb is in the present indicative, not the subjunctive.  We have sit because iudicabis sets up an indirect question.

desperandum in sentence 1 modifies the general circumstance, which is conceived as a neuter idea:  it must not be despaired.

tibi in sentence 2 is not a dative of agent, which is the norm with passive periphrastics.  Rather, it is simply an indirect object.