We are going to emancipate ourselves from mental slavery because whilst others might free the body, none but ourselves can free the mind. Mind is your only ruler, sovereign. The man who is not able to develop and use his mind is bound to be the slave of the other man who uses his mind.
As modern-day neuroscience tells us, we are never in touch with the present, because neural information-processing itself takes time. Signals take time to travel from your sensory organs along the multiple neuronal pathways in your body to your brain, and they take time to be processed and transformed into objects, scenes, and complex situations. So, strictly speaking, what you are experiencing as the present moment is actually the past.
Evil is the vulgar lover who loves the body rather than the soul, inasmuch as he is not even stable, because he loves a thing which is in itself unstable, and therefore when the bloom of youth which he was desiring is over, he takes wing and flies away, in spite of all his words and promises; whereas the love of the noble disposition is life-long, for it becomes one with the everlasting.