Vibhuti, the Sacred Ash
Sadhguru explains that when prepared properly, the sacred ash Vibhuti has certain qualities that enable it to be a great medium for transmitting energy. It is also used as a constant reminder of one's own mortality. Ignoring mortality is to live in a fundamental state of ignorance - keeping a reminder is a means to go beyond the limitations of the physical.
Quotes from this Video
“Mind is a fantastic gift to humanity. But what a horrible thing people may have made out of it.” —Sadhguru