Challenge of Spirit is a Klingon ritual that is taken by warriors that wish to hunt the dangerous animals native to the worlds of the Klingon Empire. Essentially, it was a way for Klingons to come to terms with the life they are about to take and is seen as a sign of respect for nature.
The Challenge consists of meditation and bathing which signifies purification of both mind and body. The Klingon who is on the hunt then calls upon the Spirit of the animal they are about to kill, where the hunter asks permission to take what they need. Once the kill is completed, the warrior must thank the Spirit and all the meat of the body is taken with nothing wasted. This is because the meat and bone and all that was the creature is seen as a gift from the Spirit of the animal. This all forms part of the cycle of life and death in Klingon beliefs.