It is said that if you do not meditate, you will not gain certainty; If you do, you will. But what sort of certainty? If you meditate with a strong, joyful endeavour, signs will appear showing that you have become used to staying in your nature. The fierce, tight clinging from dualistically experiencing phenomena will gradually loosen up, and your obsession with happiness and suffering, hopes and fears, and so on, will slowly weaken. Your devotion to the teacher and your sincere trust in his instructions will grow. After a time, your tense, dualistic attitudes will evaporate and you will get to the point where gold and pebbles, food and filth, gods and demons, virtue and non-virtue, are all the same for you — you will be at a loss to choose between paradise and hell! But until you reach that point (while you are still caught in the experiences of dualistic perception), virtue and non-virtue, buddha fields and hells, happiness and pain, actions and their results — all of this is reality for you.

-- His Holiness Dudjom Rinpoche