I know that images of Mohammed and Allah are forbidden in Islam, but when people read about Mohammed, for example, and form an idea of his personality, are they allowed to form a pictorial image of him in their imagination? Or for Allah? Personally, when I read about any historical character in detail, an image of him tends to pop into my head of its own accord, whether or not there exist any pictures of him or her, based on what I understand people of that person's time, place and position to have looked like. What is the position of Islam towards such images?