The instances of exemplary comparison and, later, of identification with an exemplar discussed in the book cover a wide chronological spread from Homer to Petrarch, a range of languages and types of poem, yet there are many basic similarities which persist throughout, combined with developments characteristic of a particular stage in the tradition. The choice and portrayal of particular exemplars reflects the literary, historical, legendary, religious, and cultural traditions prevailing in a particular society at a particular time. These are usually mainly transmitted through the medium of writing, but they are no doubt also influenced by oral tradition. The epics of Homer have their origins in a pre-literate period, and are based on oral-formulaic traditions which predate written texts.

The general function of exemplary comparisons and identifications is that of emphasis and embellishment, lending weight and the authority of tradition to the expression of praise or blame. This may have different realizations, according to the type of work. In the epics of Homer and Virgil, the placing and function of examples is largely determined by the demands of the narrative. Indeed it is probable that exemplary comparison was originally a device of narrative. In non-narrative and lyric verse, the placing of examples is largely determined by the relative degree of prominence attaching to specific parts of the poetic structure, for instance the beginning and end of a stanza or poem. The wide range of types of poem and subject-matter in this very large group is matched by a correspondingly wide range of variations on the basic function of emphasis and embellishment.