They will convince her or put her over the edge?

Hi there,

Where is the origin of "putting someone over the edge"? Is that similar to "pushing someone over the edge"?

best wishes,
Fuan-Jui

The image that is called up is a cliff. But I believe it refers to the edge, the border between sanity and insanity.

Merriam-Webster online:
Edge -- a point near the beginning or the end; especially : BRINK, VERGE. On the edge of disaster.