Tahir Pasha assigned me a room when I was staying in his residence, and every night before sleeping, I would spend around three hours going over the books I had memorized. It would take me three months to go through the lot. Thanks be to God, all those works became steps ascending to the truths of the Qur'an.
Philiosophers like Hume and Descartes and Hobbes saw things similarly. They thought that mental images and ideas were actually the same thing. There are those today that dispute that, and lots of debates about how the mind works, but for me it's simple: Mental images, for most of us, are central in inventive and creative thinking.