And due to rise of Ayu-karma, the duration of human, etc. embodied forms is found existing. So long as the rise of Ayu-karma continues, till then even on meeting with several diseases, etc. (external) causes, the bondage with the body does not end. And when the rise of (species of) Ayu-karma ends, then even on making several efforts there remains no bondage with body; at the same very instant soul and body become separate.
In this world (of transmigratory existence) the cause of birth, life and death is Ayu-karma only. When rise of new Ayu-karma starts, then birth in new embodied form takes place. And so long as the rise of Ayu-karma continues, till then life remains by existence of vitalities in that embodied form. And when the rise of Ayu-karma ends then death is caused by dissociation of vitalities in that embodied form. One should know that such is the natural instrumentality of Ayu-karma; none else is the creator, destroyer or protector.
Further, as someone wears new dress (cloth), he keeps on wearing it for some period, then quits it and puts on other dress; similarly, Jiva occupies new body, he keeps on occupying that body for some period, then quits it and (again) occupies another body. Therefore, birth, etc. are from bodily association point of view.
Jiva (soul) is assuredly eternal and devoid of birth, etc., nevertheless, the illusioned Jiva does not think of past and future, therefore, he keeps himself continuously busy in the activities concerning to the present embodied form only, believing his own existence to be only till the duration of the present embodied form.
In this way, the duration of embodied existence due to rise of Ayu-karma is to be known.