The Great Tantra of Vajrasattva ~ The Heart of Enlightenment...

When you run after your thoughts, you are like a dog chasing a stick: every time a stick is thrown, you run after it. Instead, be like a lion who, rather than chasing after the stick, turns to face the thrower. One only throws a stick at a lion once.

Milarepa 

“Just as it is known that an image of one's face is seen depending on a mirror but does not really exist as a face, so the conception of "I" exist dependent on mind and body, but like the image of a face the "I" does not at all exist as its own reality."   Nagarjuna 

"Thanks to impermanence, everything is possible."    Nagarjuna