Mental activity in the daytime creates a latent form of habitual thought which again transforms itself at night into various delusory visions sensed by the semi-consciousness. This is called the deceptive and magic-like Bardo of Dream.
MilarepaIn horror of death, I took to the mountains - again and again I meditated on the uncertainty of the hour of death, capturing the fortress of the deathless unending nature of mind. Now all fear of death is over and done.
MilarepaLife is short and the time of death is uncertain; so apply yourself to meditation. Avoid doing evil, and acquire merit, to the best of your ability, even at the cost of life itself. In short: Act so that you have no cause to be ashamed of yourselves and hold fast to this rule.
Milarepa