dum docent, discunt, Sen. E. 7, 8, while they are teaching, they are learning, or, by teaching they learn. nīmīrum didicī etiam, dum in istum inquīrō, artificum nōmina, V. 4, 4, preposterous as it may seem, in hunting up evidence against the defendant, I have actually learned artists’ names. The main action is often one not anticipated or desired: as, ita dum pauca mancipia retinēre volt, fortūnās omnīs lībertātemque suam perdidit, Caecil. 56, so in her attempt to keep a few human chattels, she sacrificed all her possessions and her own liberty. dum vītant stultī vitia, in contrāria currunt, H. S. 1, 2, 24, while fools essay a vice to shun, into its opposite they run. Sometimes with the perfect: as, dum Alexandrī similis esse voluit, L. Crassī inventus est dissimillimus, Br. 282, from his desire to be like Alexander, he came out just the opposite of Crassus.
(B.) dum, quoad, quamdiū (dōnec), all the time while.
[1999.] dum, quoad, or quamdiū, all the time while, often has as correlative tamdiū, tantum, tantummodo, tantisper, usque, or ita. When tamdiū is used, quam often stands for quamdiū.
[2000.] (1.) When the main verb is present or future, the protasis with dum, quoad, or quamdiū, all the time while, is usually in the same tense as the main verb: as,
mane dum scrībit, Pl. B. 737, wait while he writes. aegrōtō dum anima est, spēs esse dīcitur, Att. 9, 10, 3, as long as a sick man has breath he is said to have hope. vidua vīvitō vel usque dum rēgnum optinēbit Iuppiter, Pl. Men. 727, may’st widowed live e’en long as Jupiter shall reign. ego tē meum esse dīcī tantisper volō, dum quod tē dignumst faciēs, T. Hau. 106, I’ll have thee called my son but just so long as thou shalt act as doth become thee. dum Latīnae loquentur litterae, quercus huic locō nōn deerit, Leg. 1, 2, as long as Latin literature has the gift of speech, this spot will not lack its oak ([1733]). quamdiū quisquam erit quī tē dēfendere audeat, vīvēs, C. 1, 6, as long as there shall be a soul who will venture to defend you, you shall live on. discēs quamdiū volēs, tamdiū autem velle dēbēbis quoad tē quantum prōficiās nōn paenitēbit, Off. 1, 2, you shall study as long as you want to, and it will be proper for you to want to, as long as you are satisfied with your progress. dandum hordeum et furfurēs usque quaad erunt lactantēs, Varro R. R. 2, 7, 12, give them barley and bran as long as they are sucklings. quoad, as long as, is not found in Terence.
[2001.] (2.) With quamdiū the perfect is used when the main verb is perfect; with dum or quoad the perfect or imperfect is used when the main verb is perfect or pluperfect, and the imperfect usually when the main verb is imperfect: as,
([a.]) quōrum quamdiū mānsit imitātiō, tamdiū genus illud dīcendī vīxit, DO. 2, 94, as long as the imitation of these men lasted, so long was that style in vogue. tenuit locum tamdiū quam ferre potuit labōrem, Br. 236, he held the position as long as he could stand the work. In this use quamdiū is found first in Cicero.
([b.]) vīxit, dum vīxit, bene, T. Hec. 461, he lived well all the time he lived ([1733]). avus noster quoad vīxit, restitit M. Grātidiō, Leg. 3, 36, our grandfather as long as he lived, opposed Gratidius.