"All conditioned dharmas are like a dream, an illusion, a bubble, a shadow. Like dew and lightning. Thus they should be perceived.” What are the "conditioned dharmas" or the "compounded phenomena"? They are the conceptual elaboration subjects to change or mental activity. Conditioned dharmas take effect, yet, they are delusional without inherent existence. Like a magical display, like bubbles, like a shadow, like lightening – these are how we should perceive all phenomena.
What are the impermanent phenomena? They aren’t “real”. Since they don’t last, they are fabricated. Whatever lasts, would be the truth. We can get to understand the working of conditioned dharmas from the fabricated appearances. The phenomena (or dharmas) that we see, hear, perceive in ideas, etc., are compounded. In other words, they are “notions” that are like a dream, a bubble, and a shadow. Should we keep these notions in mind, we wouldn't grasp or cling on anything. External notions or displays will dissolve eventually. Our minds would be free from all obscurations and obstacles. Our work is to surpass these obscurations and obstacles. Eventually, we can understand the working of our Buddha nature.
What is Buddha nature? In Chan, they refer to it as the "present". What is the "present"? It is the state free from conceptual activity. Should you think and fabricate anything, it is unreal and imaginary. What is the "present"? The perception, the awareness, the realization of the moment. Wherever you are, you are present. When you return home, you're present. When you're receiving Dharma teaching, you're present. Experience every moment and instant in life fully. Whose moment? Our original mind. We should practice and apply this life so we'd be free from attachments.