XV. When I say that the thought of death is now in my mind, and that there is no other thought in my mind other than the thought of death, and that the meaning of the word “death” within my thought of death is only the thought that I am thinking while I am thinking this thought of death, but while I cannot think another thought other than this thought of death (while I am thinking this thought of death), then how can I know while I am thinking of death that this death I am thinking of is the true thought of death?