Valentine and Proteus, two longtime friends, disagree heartily on whether, as Valentine thinks, the most important thing in life is to travel and to learn the wonders of the world, or whether Proteus is right in believing nothing to be more important than love. The two friends part for a time when Valentine travels to Milan, to seek advancement and honor in the palace of the duke. He pleads with Proteus to join him in the venture, but Proteus is too much in love with Julia to leave her side for even a short time. Julia is a noble and pure young girl, who has many suitors. Proteus at last wins her heart and the two are happy in their love.

Valentine journeys to Milan, and there he learns that his friend is right about the importance of love. Valentine meets the duke’s daughter, Silvia, and falls instantly in love with her. Silvia returns his love, but her father wants her to marry Thurio, a foolish man with no personal charms but much land and gold. Valentine longs for Silvia but sees no chance of persuading her father to consent to his suit. Then he learns that Proteus, whose father is ignorant of Proteus’s love affair and wishes his son to educate himself by travel, is soon to arrive in Milan.

The two friends have a joyful reunion, and Valentine proudly presents his friend to Silvia. To Proteus he praises the virtue and beauty of his beloved, and when they are alone, Valentine confides to Proteus that, since Sylvia’s father refuses to give her to anyone but Thurio, he plans to fashion a rope ladder and steal Silvia from her room and marry her. Valentine, asking his friend to help him in his plan, is too absorbed to notice that Proteus remains strangely silent. The truth is that Proteus, at the first sight of Silvia, forgets his solemn vows to Julia (sealed before he left her with the exchange of rings), forgets his oath of friendship with Valentine, and determines to have Silvia for his own. With protestations of self-hatred for betraying his friend, Proteus tells the duke of Valentine’s plan to escape with Silvia from the palace. The duke, forewarned, tricks Valentine into revealing the plot and banishes him from Milan on penalty of his life.

While these events are taking place, Julia, thinking that Proteus still loves her and grieving over his absence, disguises herself as a page and travels to Milan to see her love. She is on her way to Milan when Valentine is forced to leave that city. Valentine, not knowing that his onetime friend betrayed him, believes Proteus’s promise that he will carry letters back and forth between him and Silvia.

With Valentine out of the way, Proteus proceeds to get rid of Thurio as a rival. Thurio, foolish and gullible, is an easy man to trick. One night, Proteus and Thurio go to Silvia’s window to serenade her in Thurio’s name, but Proteus uses the occasion to sing to her and to make protestations of his love for her. Julia, in the disguise of a page, stands in the shadows and hears his betrayal of her as well as Silvia’s response that she will love no one but Valentine. She also accuses him of playing false with Julia, for Valentine tells her of his friend’s betrothal.

Calling herself Sebastian, Julia, still in the dress of a page, becomes employed by Proteus to carry messages to Silvia. One day, he gives her the ring that Julia herself gave him and tells her to deliver...