A metaphor is a comparison used to describe something without using the terms “like” or “as.” Shakespeare’s works are filled with elaborate metaphors of all sorts. In A Midsummer Night’s Dream in particular, natural phenomena are often used as metaphors to describe various situations or to mock romantic conventions in literature and theatre.
"Your eyes are lode-stars and your tongue's sweet air..."See in text(Act I - Scene I)
Helena uses several expressive metaphors here to emphasize the qualities that Hermia has that have made Demetrius fall in love with here. In this case, Hermia’s eyes are called “lode-stars” and her tongue is “sweet air.” Both cases refer to Hermia’s ability to inspire, enchant, or guide, in the sense that her eyes and words have led Demetrius to her. A “lode-star” refers to a guiding star, like the North Star, and the noun “air” here refers to the musical quality of her voice and words.
"But earthlier happy is the rose distill'd
Than that which, withering on the virgin thorn
Grows, lives, and dies, in single blessedness...."See in text(Act I - Scene I)
The term “distill’d,” or “distilled,” means to be purified. In Shakespeare’s time, for a woman to be “pure” she was expected to either remain celibate and virginal or to choose to love one person whom she would marry. When Hermia asks Theseus what will happen if she refuses to marry Demetrius, he replies that she can either become a nun or be executed. Since there was incredible value placed on romantic love and marriage during this time, Theseus suggests that Hermia marry Demetrius. He says that her life as a nun would resemble that of “the rose” that simply “grows, lives, and dies”—or in other words, it would involve no “meaningful” life changes.
"War, death, or sickness, did lay siege to it,
Making it momentany as a sound,(145)
Swift as a shadow, short as any dream,
Brief as the lightning in the collied night..."See in text(Act I - Scene I)
"Swift as a shadow" comes from a 12th-century proverb "to flee like a shadow." Lysander uses this metaphor to highlight the brevity of love and its ephemeral nature. Hermia complains that the biggest obstacle to love is choice. But Lysander notes that the forces of nature often conspire against love even if one gets to choose, and death, war, or sickness cut it short. These lines begin the play in a more dramatic tone than one would expect from a comedy. There is a darker theme that runs throughout the play and underscores the lighter romantic themes and tropes. This darker theme questions the truth and value of a love that is so fickle it can be drawn from perception and so ephemeral that it can change its object frequently over the course of this short play.
Adamant was a very strong kind of rock, otherwise unidentified, that was originally believed to be unbreakable. During Shakespeare’s time, adamant was also associate with lodestone, a rock made of magnetite. So, when Helena compares Demetrius to “hard-hearted adamant” she is saying that she is drawn to him like metal to a magnet.