Chogyam Trungpa in The Tantric Path of Indestructible Wakefulness, a part of The Profound Treasury of the Ocean of Dharma:

The absence of grasping and fixation is like flying in an airplane. When we rise above the clouds, we begin to realize that upstairs there is a blue sky all the time. We realize that the sun is always shining, even when it is cloudy and rainy down below. There is blue sky all the time, and that blue sky is free from clouds.