When Divine love descends upon human love, then by the meeting of the two a bright and perfect shadow of the Holy Spirit is created in the heart of man. At this stage of communion the light of the Holy Spirit is very bright. Extraordinary feats of power, which we have just mentioned, proceed from such people because the light of the Holy Spirit is ever present with them and dwells within them and this light never departs from them and they are never separated from it. That light issues from them every moment with their breath and falls upon everything with their look and exhibits its brightness in their words. The name of this light is the Holy Spirit, but this is not the Holy Spirit itself for the Holy Spirit itself is in heaven. This Holy Spirit is a reflection which dwells forever in pure breasts and hearts and brains and does not depart from them even for a moment. Anyone who thinks that at any time the Holy Spirit with all its effects departs from them is entirely based upon falsehood and insults the holy elect of God Almighty by his dark thought. But it is true, that although the real Holy Spirit remains at its station, its reflection, which is metaphorically called the Holy Spirit, enters into the breasts and hearts and brains and limbs of those who, after attaining the station of immortality (Baqa) and communion with God (Liqa), become fit for the perfect love of God Almighty with all its blessings to descend upon their pure and undefiled love. When that Holy Spirit descends it establishes a relationship with that person like the relationship of the soul with the body. It becomes the faculty of sight and works in the eyes, and putting on the garment of the faculty of hearing bestows spiritual sense on the ears, it becomes the power of speech of the tongue and the righteousness of the heart and the intelligence of the brain and flows through the hands and affects the feet. In short, it lifts all darkness from the body and illumines it from the hair of the head to the nails of the toes. Were it to depart for a moment, darkness would immediately take its place. It is such a good companion for the perfect people that it does not depart from them for a moment and to imagine that it can depart from them would be a confession that after entering into light they fall again into darkness, and that after having been protected and made secure their evil directing minds revert to them and that after they are bestowed spiritual senses, those senses are rendered useless and are suspended….
Every light, comfort, satisfaction., blessing, steadfastness, and every spiritual bounty, is bestowed upon the elect through the Holy Spirit. As for the disbelievers and the wicked, Satan has been appointed their evil companion for all time so that he might spread darkness over them every moment and should not leave them alone in their standing and sitting and movement and rest and sleep and waking. Similarly for those who are close to God, the Holy Spirit has been appointed as a good companion for all time so that it should constantly rain down light upon them and should support them every moment and should not depart from them at any time. It is obvious that in contrast with the evil companion who is the servant and colleague of the wicked, it is necessary that the good companion should always keep company with those who are close to God, and the Holy Qur’an confirms this.
Excerpted from The Essence of Islam Volume II (pp 170–172)