Yogācārabhūmi-śāstra, Volume 34 (41)

Original text: 云何复由别离行故。观无常性。谓依内外二种别离。应知诸行是无常性。依内别离无常性者。谓如有一先为他主。非奴非使。能自受用。能驱役他作诸事业。彼于后时退失主性。非奴使性。转得他奴。及所使性。于主性等。名为别离无常之性。

Explanation: How does one contemplate the nature of impermanence by means of the practice of separation? Relying on the two kinds of separation—internal and external—one should know that all formations are impermanent in nature. The meaning of relying on internal separation to contemplate the nature of impermanence is this: suppose there is a person who was formerly the master of others, neither a slave nor an errand-runner, able to enjoy things himself and able to direct others to carry out various undertakings. Later, this person loses his position as master, losing the nature of a master as well as the nature of being neither slave nor errand-runner, and instead acquires the nature of being another's slave and errand-runner. For such a person, the nature of being a master and so forth is called the nature of impermanence through separation.