Yogācārabhūmi Śāstra, Fascicle 34 (26)

Original text: 云何观察园事变异无常之性。谓先观见。诸园苑中药草丛林。华果枝叶。悉皆茂盛。青翠丹晖。甚可爱乐。复于后时。见彼枯槁。无诸华果。柯叶零落。火所焚烧。水所漂荡。见是事已。便作是念。如是诸行。其性无常。余如前说。

Explanation: How does one observe the impermanent and mutable nature of garden matters (udyāna-vastu)? Previously, one saw that in all the gardens and parks, the herbs, groves, flowers, fruits, branches, and leaves were all lush and flourishing, with red blossoms and green leaves, very delightful to behold. Then, at a later time, one sees these plants withered, no longer bearing flowers or fruits, their branches and leaves fallen and scattered, or burned by fire, or swept away by water. After observing these phenomena, one thinks in the mind: such conditioned formations are truly impermanent in their nature.