According to Sthiramati, though samsara has the nature of nirvana, in ordinary beings true reality is obscured by their tendencies of clinging to a self and really existing phenomena. Thus, they do not see emptiness, which actually exists, but they naturally perceive the actually nonexistent phenomena of apprehender and apprehended, just as when mistakenly not seeing an existent rope, but seeing it as a nonexistent snake.
Bodhisattvas lack the clinging to a self and phenomena and thus they naturally see true reality—emptiness—while not seeing any duality, just as correctly seeing an existent rope, while not seeing it as a nonexistent snake. When existent emptiness—true reality—is seen and the nonexistent characteristics of apprehender and apprehended are not seen anymore, the alaya-consciousness—the dependent nature—has undergone the fundamental change. This fundamental change is liberation and nirvana.
Just as people liberated from bondage can do what they please, once this fundamental change occurs, bodhisattvas are liberated because they have gained mastery over their minds, which abide like space without any appearance of characteristics. Thus, no matter what they encounter, they are able to act as they please without being bound by any attachment or aversion.