Act V, scene 1 begins when Theseus and Hyppolita have heard the story of Demetrius, Helena, Lysander and Hermia. Hyppolita's words are a response to Theseus, who doesn't believe the story and compares the stories told by the lovers to the imaginings of madmen and poets ("The lunatic, the lover and the poet / Are of imagination all compact", i.e. they all have the same imagination).
Hyppolita's words can be paraphrased as follows:
But when the story of last night is told in full,
and [we see that] the minds/imaginings of the four of them are all "transformed" in the same way,
this testifies to more than just the creation of the imagination,
and [what they say] grows to something more true or permanent,
albeit something strange and to be wondered at.
A few additional notes:
- "something [of great constancy]" contrasts with "airy nothing" in Theseus' words. (Chaudhuri)
- "constancy" does not only suggest "something permanent and therefore true" but also "that the lovers' relationships have progressed beyond 'fancy' or casual attraction to firm love". (Chaudhuri)
- "[T]he word 'constancy' also means 'fidelity' and refers to the newfound steadfastness of loved confirmed in marriage." (R. A. Foakes)
Sources:
- Shakespeare: A Midsummer Night's Dream. Edited by Sukanta Chaudhuri. The Arden Shakespeare, Third Series. Bloomsbury, 2017.
- Shakespeare: A Midsummer Night's Dream. Edited by R. A. Foakes. The Cambridge Shakespeare. Cambridge University Press, 1984.
- Shakespeare: A Midsummer Night's Dream. Edited by Stanley Wells. The New Penguin Shakespeare. Penguin, 1995.