It is here and now. The evidence is obvious. It is in your face, no explanation needed. The damage speaks for itself. Pain the past is anger.
Anger is resentment over being hurt.
When anger is not immediately expressed with the hurt that cause it, it is stored in our emotional debt bank. There it meets up with other stored up anger. The longer you hold onto anger the more distorted it becomes once you finally release the anger. The depletion of psychic energy to withhold anger is called depression. The energy required to keep anger from expresion is part of the total energy available to solve problems, be creative, love, motivate yourself, and live your life.