From A Glossary of Literary Terms, M. H. Abrams and Geoffrey Harpham
Epic similes are formal, sustained similes in which the secondary subject, or vehicle, is elaborated far beyond its point of close parallel to the primary subject, or tenor.
For example, when Odysseus returns to his men after having been to Circe’s home, they are described thus:
When they saw me they were like farmyard calves
Around a herd of cows returning to the yard.
The calves bolt from their pens and run friskily
Around their mothers, lowing and mooing. (10.434-7)
