The first bardo comes at the very moment of death, when there dawns the Clear Light of the Ultimate Reality. This is the very content and substance of the state of liberation, if only the soul can recognize it and act in a way to remain in that state. The instructions intended to be read at the moment of the person's death are designed to help him do this.  He is told, first of all, to embrace this supreme experience not in a selfish and egoistic way but rather with love and compassion for all sentient beings.  This will aid him in the second step, which is to realize that his own mind and self is identical with the Clear Light, implying that he himself IS the Ultimate Reality, "the All-good Buddha", transcending time, eternity, and all creation. If he can recognize this while in this supreme state at the moment of death, he will attain liberation - that is, he will remain in the Clear Light forever. This condition is called the "Dharmakaya", the highest spiritual body of the Buddha.