This can be answered in a variety of ways. One way would be to take Eliezer's own reactions and experiences when he is liberated. The ability to stare back in the mirror at his own reflection and his own lack of recognition for the vision he sees might be a fitting realization for what most prisoners would have done when they were freed. The idea of being able to physically and visibly see all the changes that were present in their own appearance could be one thing done when freed. Imagine what this must have been like on both experience based and symbolic levels. On one hand, to actually see the change undergone and then simultaneously to wonder from where to where one has come would be stunningly powerful. After everything that Eliezer endures, this is his first experience when he is freed and it helps encapsulate everything that had transpired.