In Act I, Scene I (line 140), Hermia speaks and gives the first of many mentions to "eyes". What juxtaposition is set up by this?
There is much mention of "eyes" in the first act and throughout the play the theme of seeing, or not seeing, is abundantly evident. The juxtaposition set up in Act 1 by the mention of eyes repeatedly is to let the audience understand that the play deals with the idea that love can't always be understood by using the eyes alone and that love tends to make fools of people. In the play, Shakespeare has characters who fall in and out of love instantly due to the magical qualities of a flower. Lysander and Demetrius both love Hermia, then they both love Helena, then Demetrius loves Hermia and Lysander is back with Hermia. Titania falls in love with the ass-headed fool, Bottom. Even though none of these characters loses his or her sight during the play, Demetrius, Lysander, and Titania all lose the ability to "see" with whom each professes to love. Even the method in which the drops from the magic flower works deals with the eyes. Puck must annoint the eyelids of the sleeping individual in order for it to work and then, when the individual wakens, the first person he or she SEES is the new object of that person's love. It's all about the eyes! Puck even tells us at the end that if we don't like what we've seen, we can pretend we just had a dream.