Answer:
Speaking of the nightingale that she heard, is a metaphor to the unfamiliar perhaps, as Romeo may be as good as Paris but if he is , he would not be present or here to enjoy.
It is the metaphor lark that is always present in comparable that has some linkage.
Other to that is the time of the day it is not even daytime, so Juliet is questioning his character of getting up and leaving.
It just so happens to be post dawn and first bird call of that morning.
Explanation:
Adaption to this is scene with the nurse;
Faith, here it is.
Romeo is banishèd, and all the world to nothing
215 That he dares ne'er come back to challenge you.
Or, if he do, it needs must be by stealth.
Then, since the case so stands as now it doth,
I think it best you married with the county.
Oh, he’s a lovely gentleman.
220 Romeo’s a dishclout to him. An eagle, madam,
Hath not so green, so quick, so fair an eye
As Paris hath. Beshrew my very heart,
I think you are happy in this second match,
For it excels your first. Or if it did not,
225Your first is dead, or ’twere as good he were,
As living here and you no use of him.
