Yogācārabhūmi-śāstra, Volume 34 (33)

Original text:云何观察光明变异无常之性。谓由观见种种明闇。生灭变异。见此事已。便作是念。如是诸行。其性无常。余如前说。云何观察男女承奉所有变异无常之性。谓观见彼。或衰或盛。不久坚住。见此事已。便作是念。如是诸行。其性无常。余如前说。

Explanation: How does one contemplate the impermanent nature of the alterations of light? One sees the arising, ceasing, and alteration of various forms of brightness and darkness; having observed these phenomena, one then has this thought: such formations are truly impermanent in nature. The rest is as stated before. How does one contemplate the impermanent nature of the alterations in the mutual affection and attendance between men and women? One observes that their mutual affection wanes or flourishes, flourishes or wanes, and cannot endure for long; having observed these phenomena, one then has this thought: such formations are truly impermanent in nature. The rest is as stated before.