In the Satipatthana Sutta: The Discourse on the Arousing of Mindfulness, the Buddha gives the Nine Cemetery Contemplations which are instructions for observing the dissolution of the body after death. The intent of this practice is to develop non-attachment to the body by observing its deterioration, shocking us out of infatuation and into a realization that the body is as it is, progressing from youth to maturity to old age and then through death and decomposition.
For the past 2500 years, monks and nuns have gone to the charnel grounds to witness firsthand these facts of existence. In the West since the rise of modern medicine and hospitals, we’ve largely been separated from this process and have developed a certain squeamishness about it.
Interestingly, one no longer has to go to the charnel grounds as the sequence is observable through time lapse photography on YouTube (as I discovered when I was looking for something else).
As we approach the witching hour of Halloween and the Day of the Dead celebrations, working with one of what Pema Chodron calls the “three methods for working with chaos,” can be a powerful tool for increasing our understanding and deepening our practice.