Once a thought has been learned in a soul, the physical faculties of sense perception and imagination become unnecessary, and as a person acquires more thoughts, their soul becomes less connected to their body.[58] For Avicenna, different from the normal Aristotelian position, all of the soul is by nature immortal. But the level of intellectual development does affect the type of afterlife that the soul can have. Only a soul which has reached the highest type of conjunction with the active intellect can form a perfect conjunction with it after the death of the body, and this is a supreme eudaimonia.