What dose my child, you have hit on a capital idea mean?

1)On Act I (page 24) Juliet had been finally told that the man she fell in love with is the son of her family’s biggest enemy. Juliet then says:

“My only love sprung from my only hate!

Too early seen unknown, and known too late!

Prodigious birth of love it is to me,

That I must love a loathed enemy.”

Eventhough she now knows who Romeo actually is, she still seem to understand that she loves her enemy. That said, we can assume that Juliet doesn’t mind if Romeo is her family’s enemy, since she is already in love with him and she will love him anyway.  

2)On Act II (page 28), Romeo says:

”I take thee at thy word:

Call me but love, and I'll be new baptized;

Henceforth I never will be Romeo.”

Romeo knows that Juliet was supposed to be his enemy and that their families have a long history of issues already. However, he is willing to change his own name in order to stay with Juliet as he loves her and wants to be with her.

After analysing both sentences mentioned above, it is clear that whatever happened between their families doesn’t really matter to Romeo and Juliet. It does not affect the feelings they have for one another and will not stop them from loving each other; therefore their differences do not define them.