From the Prologue:
When we wish to emphasize the importance of something, we say that it is a matter of life and death. A matter of primary importance for those of us who believe in heaven and hell perhaps even the most important is our departure from the world and the life after death. After we are born, the only thing we can take for granted is that at some point we will die. In Holy Scripture, death is called the way of all the earth (3 Kingd. 2:2), because it is the road which we will all travel. All of us, therefore, must contemplate our death and prepare to encounter it. Christ himself stresses this, saying: Therefore, be ready, for it is at an hour which you do not expect that the Son of Man will come. (Matt. 24:44)
The saints of the Church stress that the remembrance of death is a great and enduring support in our spiritual struggle, both by halting our slide into sin and as a God-given strength in the exercise of virtue. Since we completely forget about death due to the cares and distractions of daily life, sometimes willfully, God reminds us of it in different ways, most poignantly when a family member or friend departs this life for the next.
In the present work we will try to see what it means for a lay person to be mindful of the time of death and how this mindfulness benefits the spiritual life. Everything we say is based on the experiences of the holy Fathers [of the Church] who lived in expectation both of their eventual departure from this life and of the coming of the Lord.