Final answer:
Romeo is struck by Juliet's beauty at the Capulet's party, declaring that he has never known true love or beauty until that moment, marking the onset of their star-crossed romance.
Step-by-step explanation:
When Romeo says, "Did my heart love till now? Forswear it, sight! For I ne'er saw true beauty till this night," he is expressing his instant infatuation upon seeing Juliet for the first time. In this line from William Shakespeare's Romeo and Juliet, Romeo suggests that he has never truly known beauty or love until he laid eyes on Juliet at the Capulet's party. This marks a significant moment in the play as it signifies the beginning of Romeo and Juliet's tragic love story.