To L. Aelius Lamia, the friend of 1.26, and probably the consul of A.D. 2. Under the empire the Lamiae became types of ancient nobility. Cf. Juv. Sat. 4.154; 6.385. Lamia apparently is at his seaside villa. Horace playfully traces his friend's pedigree back to Homer's cannibal king Lamos, and bids him, since a storm is brewing, get in his firewood and prepare to 'loaf and invite his soul.'
quando: since, motivates ducis. As all the Lamiae are descended from Lamos, you too must derive your lineage from the founder of Formiae (which Cicero, ad Att. 2.13, identifies with Homer's Laestrygonia; Odyss. 10. 82); the parenthesis ends with tyrannus, 1. 9. hinc denominatos: derived their name from him; cf. unde (1.12.17); hinc (Verg. Aen. 1.21).
memores fastos: recording registers; cf. on 4. 14. 4. The reference here is to family records. The Lamiae do not appear in the consular fasti till A.D. 2. auctore: cf. 1.2.36. n. ducis originem: trace thy origin.
innantem: the quiet Liris (1.31.7) near its mouth overflows in marshes at Minturnae, where the Italian nymph Marica (sometimes identified with Circe) was worshiped.
late tyrannus: εὐρυδρείων. Cf. Verg. Aen. 1. 21, late regem; Epp. 1.11.26; Pliny, Epp. 3.7, latissime victor.
inutili: cf. on 3.24.48. Here proverbially worthless. Cf. vilior alga (Sat. 2.5.8; Verg. Ecl. 7.42).
aquae . . . augur: ὑετόμαντις. Cf. 3.27.10; Lucret. 5. 1086 = Verg. G. 1.388. sternit: bestrew. Cf. 4.14.32.
annosa: cf. 4.13.25; Hes. fr. 183; Arat. Phaen. 1022; Lucret. 5.1084. Tennyson's 'many-wintered crow'. Bryant's 'century-living crow.'
genium: the ghost, spiritual double, inner animistic self, birth-spirit, or guardian angel of anything. Under the influence of the Platonic doctrine of the Daimon or Guardian Angel and higher self, this conception of the popular Roman religion was deeply moralized in later literature and poetry. Cf. Plato, Tim. 90 A; Rep. 619 E; Boissier, Religion Romaine, Vol.11., p.145; Schmidt, Ethik der Griechen, 1.153; Hor. Epp. 1.7.94; 2.2. 187; 2.1.144; 2.3.210; Petron. 62; Ter. Phorm. 44; Pers. Sat. 2.3; F. Q. 2.12. 47-48; Shaks. Jul. Caes. 2.1, 'The genius and the mortal instruments'; Ant. and Cleop. 2.3, with Macbeth, 3.1; Matthew Arnold, Palladium, Scholar-Gipsy, 'To the just-pausing genius we remit | Our well-worn life, and are -what we have been'; Mrs. Browning, Son. fr. Port. 42, 'my ministering life-angel.' Phrases like indulge, care for, propitiate your genius, etc., were used colloquially like our 'be good to yourself,' 'invite your soul,' etc. 16. operum solutis: cf. on 2.9.17; 3.27.69. For solutus with abl., of. Sat. 1.6.129.