For the (true) astrologer, the ultimate purpose of reading one's horoscope (one's journey through this life) is to show, in a scientific manner, that the life we experience, as a result of our past actions and desires, is impermanent by nature (fleeting and non-lasting).
Death comes to all living beings and the manner of death, verifiable through the divine light of jyotish, is already determined at the moment of birth. To quote a favourite teacher;
"We all have our own way of coming and going"
Diana's way was to die in a vehicle accident and nothing could change that!
She was destined to be a princess and destined to endure a loveless marriage... all this; her birth, life and death, is clearly visible in her horoscope. And likewise is our own destiny.
This life is our own creation and, when the experiences (we ourselves have created) have ran their course, we leave behind this physical body and consciousness moves on
to another existence, another plane...This we call death!
And it's This, the illusory nature of existence, that is the greatest truth jyotish
(the eternal eye of the Veda) can reveal to us.