What does "why" mean in this context? [duplicate]

Have you ever thought of it Susie, and yet I know you have, how much these hearts claim; why I dont believe in the whole, wide world, are such hard little creditors - such real little misers, as you and I carry with us, in our bosoms every day. I cant help thinking sometimes, when I hear about the ungenerous, Heart, keep very still - or someone will find you out!

I found this in Emily Dickinson's letter. Does "why" here mean the "reason" Emily doesn't believe the world?

Solution 1:

In this context it is just an exclamation like "Well" or "hey". In this context it is not related to a reason.

Solution 2:

Why is an interjection here and Cambridge records this use as

mainly US or old-fashioned: used to express surprise or anger:

• Why, I've never seen anything like it!

If you wish to know more about it, this thread will give you all the answers.