If there are obstacles, it cannot be space,

If there are numbers, it cannot be stars,

If it moves and shakes, it cannot be a mountain,

If it grows and shrinks, it cannot be an ocean,

If it must be crossed by a bridge, it cannot be a river,

If it can be grasped, it cannot be a rainbow.

These are the six parables of outer perception. 

Milarepa 

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