Are Hallucinations Normal?

The author once had a weird, wonderful vision induced by a migraine, but believes other hallucinations are common variations of pathologies.

Question: What was the visual hallucination you once experienced?
Siri Hustvedt: You know, this is a story I love and there are moments that I'm sorry it never happened again.  It only happened to me once.  I was in my 30's, I remember I was reading Svevo, it was "The Confessions of Zeno," there's actually a new translation, but I was reading the old one.  And I looked—I was lying in bed and I looked down at the floor and there was a little pink man and a pink ox, and they were about this tall, moving and beautifully articulated.  So, lovely.  And they gave me a very good feeling.  I had no fear, no distress, just a feeling of fascination, friendliness, and pleasure.  And I watched them for a while without saying to myself—I did not say "You're having a hallucination."  I didn't say it.  I just looked at them and then they disappeared.  This hallucination was followed by a migraine.  And I didn't know at the time, I had no idea, they too have a name, it's called Lilliputian hallucination.  It is associated with migraine.  But other people—sometimes people who have had stroke can also have these visual hallucinations.
Question: Do you think many "visionary" prophets were in fact epileptics?
Siri Hustvedt: Well, they may have been epileptics, but I think again, it's always so complicated in medicine to draw a line between normal experience and what's pathological.  I mean, this is not so easy to do.
So, for example, it does seem that something like auditory hallucinations, I've had it a number of times.  The only time I have it now is when I'm dropping off to sleep, I will often hear voices.  Men's voices, women's voices, usually short sentences, very hard for me to remember what they said in the morning. 
In Nabokov's "Speak, Memory," he has a wonderful little passage about exactly that, both his hypnogogic hallucinations of a visual kind before he's going to sleep, and hearing voices.  It's a beautifully written little passage in "Speak, Memory."  You know, Nabokov was clearly not mad.  I don't feel mad.  And many people, and there have been certain studies that have been done that many, many people at one time or another have experienced auditory hallucinations.  It becomes part of a pathology, I think, when, for example, in schizophrenia... people who have schizophrenia are often tormented by voices talking all the time and jabbering away, telling them to do terrible things.  That becomes a curse.  And also in schizophrenia, usually the presence of the voices is explained in a delusional way.  You know, like the famous CIA has planted things in your brain, or whatever.  This is very common.  Whereas, when I've had auditory hallucinations, I have always thought I was having auditory hallucinations.  I mean, once I mistook the voice of a friend for a real experience, that he was actually calling me.  But otherwise, I haven't.  So, there are normal variances of many experiences that are often regarded as pathological, such as hearing voices, or hallucination.