Allusion
An allusion is a reference to another published work. The Aeneid is a published work so by referring to it, Virgil makes an allusion. A canto is a section of a long poem - this is not a reference. A symbol is when an object represents or stands for an idea. One of the most common symbols is the heart which can symbolize love. Terza rima is a group of triplets especially in rhyme, such as when a rhyme scheme is ABA, BCB, CDC, DED