Attaining the first fruit (srotāpanna) means realizing that the five aggregates are without self, thereby obtaining the pure Dharma eye

Since beginningless kalpas, the manas has constantly grasped at the five aggregates and the eighteen realms. Why does it grasp? Because the manas regards these dharmas as "I" and "mine," and hence there is grasping. If the manas no longer regarded these dharmas as self and belonging to self, it would no longer grasp them, because it would know that grasping is useless, that craving is useless, that nothing can be held onto—that they are empty, suffering, illusory, and unreal. Once this principle is realized, grasping will gradually loosen, and one will become increasingly at ease and liberated. When a stream-enterer realizes that the five aggregates are without self, they attain the purity of the Dharma eye, and the mind's eye begins to become pure. When seeing is pure, action becomes pure; and when afflictions are completely severed, action is the purest of all.