facing death

Someday you have to face death. well, anyone who is born is sure to face death. Death is a negative energy, that is how we perceive it to be. but Tsogyal  Rinpoche who wrote the tibetan book of living and dying, has got completely something else to say. He says rejoice in death, while we are alive we never think of death and when the death comes it is too late to regret over things you haven't done and over the things you have done. How the thought of dying can be an optimistic vision? Well it is very obvious that if we think of death then we know the value of life, when we think of death then only we will know how to live. At the time of death what we think becomes the seed for the next life, I had this confusion always that how mere thought becomes the energy that determines our next birth? so i asked Tsogyal rinpoche la this question that how is this logical, so he responded as for example during my exam if i forget whatever i learnt then i might flunk and the next moment while he was saying he interrrupted himself and said no that isnt a good analogy, so then he said that it is logical. then he was explaining some things, some general things. the point i have here is that i was trying to make a connection with the master, (i know very naive to think like that or may be very wise, may be at some point of practice, he might help me)and yes my doubt was genuine. i was wondering about the thing since a long time, may be i have the question still unanswered in my mind. Responding to one of the question Rinpoche la said to that person "we have made a connection." I am sure that peerson is lucky(again very fool to think like that) . And then in the end he said if one reads his book(actually read, as in again and again quite mindfully) it is equal to having a teacher, he was insisting to read it again and again !!!