Allen and Greenough's New Latin Grammar for Schools and Colleges
J. B. Greenough, G. L. Kittredge, A. A. Howard, Benj. L. D'Ooge, Ed.

1. “Gallia est dīvīsa ” (B. G. 1.1) , Gaul is divided.
2. “locus quī nunc saeptus est ” (Liv. 1.8) , the place which is now enclosed.
3. “vidētis ut senectūs sit operōsa et semper agēns aliquid et mōliēns ” (Cat. M. 26) , you see how busy old age is, always aiming and trying at something.
4. nēmō adhūc convenīre mē voluit cui fuerim occupātus (id. 32), nobody hitherto has [ever] wished to converse with me, to whom I have been “engaged.”

[*] Note.--From this predicate use arise the compound tenses of the passive,—the participle of completed action with the incomplete tenses of esse developing the idea of past time: as, interfectus est, he was (or has been) killed, lit. he is having-been-killed (i.e. already slain).

The perfect participle used with fuī etc. was perhaps originally an intensified expression in the popular language for the perfect, pluperfect, etc.

At times these forms indicate a state of affairs no longer existing:—

1. “cōtem quoque eōdem locō sitam fuisse memorant ” (Liv. 1.36.5) , they say that a whetstone was (once) deposited in this same place. [At the time of writing it was no longer there.]
2. “ arma quae fīxa in parietibus fuerant, humī inventa sunt ” (Div. 1.74) , the arms which had been fastened on the walls were found upon the ground.

But more frequently they are not to be distinguished from the forms with sum etc.

The construction is found occasionally at all periods, but is most common in Livy and later writers.