Chayei Sarah 5775

When Eliezer brings Rivkah back to Yitzchak, Rashi notes that he tells Yitzchak of all the miracles that occurred during his searching for Rivkah. In the next verse, Onkelos explains that Yitzchak saw that her deeds were good and proper like Sarah's. Why was it necessary for Yitzchak to do so? Wasn't it enough to recognize those deeds through the miracles that occurred to Eliezer? The Brisker Rav answers that miracles don't testify for a person's nature and character; one can only see and experience those things firsthand with him/her.