Imagination is everything in our life, without imagination there would be no progress, we would have no development, the human being would remain stuck in ignorance. When one wants to do something, it is needed to resort to imagination; thought can not be manifested without it.
When you think about a book, imagination sees the book; when one hears a story, one imagines the history. If you can think without imagination you will be the first person in the history of mankind to achieve that.
Imagination has no power over thought, or rather, over our will. There exist parasite thoughts that use the imagination and weaknesses of the people to manifest themselves, for example, the glutton person sees these thoughts in his mind turned into food or delicacies. This will be enough to try to materialize them, in other words, to give life to these thoughts, and if such person does not have enough will, he will fall into temptation. If this is repeated often, it becomes an obsession.