_Sources of the Georgics._--Besides his own observation, Virgil used the following authorities: 1. Hesiod--mostly in Book i., _e.g._ ll. 276-286 (lucky and unlucky days). Cf. ii. 176, 'Ascraeumque cano Romana per oppida carmen.' 2. Books of the priests; _e.g._ i. 269 _sqq._ (what is lawful on holy days), i. 338 _sqq._ (Ambarvalia). 3. For agriculture and natural history--Greek writers like Aristotle, Theophrastus, Democritus, and Xenophon; and Latin writers like Cato and Varro. 4. Alexandrian writers for science and mythology; _e.g._ Eratosthenes for i. 233, 'quinque tenent caelum zonae,' etc.; i. 351-465, signs of weather, from the Διοσημεῖα of Aratus; iii. 425 _sqq._, the Calabrian serpent, from the Θηριακά of Nicander, whose writings were also used for the subject of bees in Book iv. 5. Lucretius, to whom Virgil is chiefly indebted, ii. 475 _sqq._, especially 490 _sqq._, 'felix qui potuit,' etc., refers to Lucretius. The idea of Lucretius, cf. v. 206-217, that man has a perpetual struggle with nature, is reflected in Virgil, but modified by his acceptance of the argument from design. Cf. i. 99, '_Exercet_que frequens tellurem atque _imperat_ arvis,' and the whole passage i. 118-159. Lucretian science is borrowed in passages like i. 89, 'Seu pluris calor ille vias et caeca relaxat spiramenta, novas veniat qua sucus in herbas'; l. 415-423 (of the habits of birds); iii. 242 _sqq._ (on the passion of love). Notice also, with Munro, Lucretian phrases like _principio_, _quod superest_, _his animadversis_, _nunc age_, _praeterea_, _nonne vides_, _contemplator_, _genitalia semina_. _Political purpose of the Georgics._--The political purpose of the Georgics is to help the policy of Augustus, which aimed at checking the depopulation of the country districts. Cf. i. 498-514, and especially ll. 506-7, 'Non ullus aratro dignus honos: squalent abductis arva colonis.' The Emperor is introduced throughout as the object of veneration. Cf. i. 24-42. _Natural scenery._--Virgil dwells on Nature in her softer aspects. Cf. phrases like ii. 470, 'mollesque sub arbore somni,' and the passage ii. 458-540 in praise of a country life. For the praise of Italy see the beautiful passage ii. 136-176, where special districts are mentioned. AENEID.--Even before the _Eclogues_ were written, Virgil had meditated the composition of an epic, perhaps, as Servius suggests, on the kings of Alba. Cf. _Ecl._ 6, 3, 'Cum canerem reges et proelia, Cynthius aurem vellit et admonuit: "pastorem, Tityre, pingues pascere oportet oves, deductum dicere carmen."' The idea of a poem in honour of Augustus was present to his mind when he wrote _Georg._ iii. 46, 'Mox tamen ardentes accingar dicere pugnas Caesaris.' The _Aeneid_ was commenced B.C. 29, and remained unfinished at Virgil's death. Servius, _vit. Verg._, 'postea ab Augusto Aeneidem propositam scripsit annis undecim, sed nec emendavit nec edidit.'