وللنفس مطاوعة للتخيل كمطاوعته للتصديق، بل أشد منه
The soul responds to imagination as it responds to assent, and sometimes even more strongly.
In tasdīq, the mind assents to a judgment. In takhyīl, an image or description evokes an emotional response. Someone may know a staged danger is fictional and still feel frightened.
An experienced effect and a true proposition are different things. The emotional force of an image does not establish demonstrative truth.