This slogan is an expression of compassion and openness. It means that whatever you experience in your life-pain, pleasure, happiness, sadness, grossness, refinement, sophistication, crudeness, heat, cold or whatever, is purely memory. The actual discipline or practice of the bodhisattva tradition is to regard whatever occurs as phantom. Nothing ever happens. But because nothing happens, everything happens.
That ”nothing happening” is the experience of openness, and that percolation is the experience of compassion.