Yoga Sūtra Chapter Three verse 43

bahiḥ akalpitā vṛttiḥ mahā-videhā tataḥ prakāśa-āvaraṇa-kṣayaḥ ||43||

External non-imaginary fluctuation is the great discarnate,
hence the covering of the light diminishes.

bahis - externalakalpitā - non-imaginaryvṛtti - fluctuation; modification; turned; set in motion, course of action, behaviour, movement; activity, function; professionmahā - greatvideha - discarnatetatas - henceprakāśa - brightnessāvaraṇa - coveringkṣaya - diminish, wasting or wearing away