Lojong 2: Life is a dream
There is little difference between dreaming and ordinary experience: they both seem completely real but are both fading memories as soon as we experience them
Conscious experience consists mostly of sense impressions. Even abstract thoughts consist of visual or auditory impressions imbued with meaning. Emotions are usually a thought colored or accompanied by a sensation in the body.
Sense impressions come to consciousness either from the environment through the sensory apparatus or from the imagination. From the point of view of experience, sense impressions from the environment may be more vivid, but otherwise there's not a great deal of difference between the two.
We can further see that when consciousness "takes delivery" of a sense impression, it's already encoded in the brain. That happens a few milliseconds after the event itself, but it has to be after, never before, not even at the same time. When consciousness becomes aware of a sense impression, the event(s) that triggered it is/are already in the past.
Everything we experience consciously, whether in a dream or in what we consider "real" life, is a memory.