Grammar: Dum + subjunctive

Like the temporal conjunction cum, there are some other temporal conjunctions -- antequam, priusquam, dum -- which are used sometimes with indicative verbs and with subjunctive verbs.

Indicative. Indicative verbs are used to describe factual situations in time:

» antequam pecuniam perdidit, Marcia valde felix erat. Before she lost her money, Marcia was very happy.

» dum pecuniam habet, Marcia felix est. So long as she has money, Marcia is happy.

» dum Samson dormit, tonsor eius caput rasit. While Samson slept, the barber shaved his head.

Subjunctive. Subjunctive verbs are used to express purpose or expectation (or failed expectation):

» priusquam eius litteras legeret, Marcus mortuus est. Marcus died before he could read the letter.

» exspectamus dum Marcia veniat. We are waiting until Marcia comes.