Sidney uses abundant local instances of simile and metaphor to display the value of poetry and argue against its detractors.
For example, he states that Menenius Agrippa, a Roman patrician, "behaves himself like a homely and familiar poet," a simile. He uses a metaphor to compare poetry to a mother who gives the "milk” of knowledge to future generations, and, as noted in the Themes section of this guide, elsewhere compares poetry to a beautiful woman.
On the negative side, Sidney uses similes to describe philosophers who use the art of poetry yet disavow it as "like ungrateful prentices [who] were not content to set up shops for themselves, but sought by all means to discredit their masters." Others who disavow poetry in the guise of Plato's "lion’s skin" are said to make "an ass-like braying against poesy." The bad poetry of England is "like an unmannerly daughter, showing a bad education, caus[ing] her mother Poesy’s honesty to be called in question." Verse with needlessly elaborate diction bears "a courtesan-like painted affectation," and poets who use too much decoration are "like those Indians, not content to wear ear-rings at the fit and natural place of the ears, but they will thrust jewels through their nose and lips, because they will be sure to be fine"
In addition to these instances, Sidney compares poetry to the art of horsemanship in various places, as discussed in the Themes section of this guide.