成唯識論演祕 3.581

3.581

心心所法有取果用，色法不然，故名為半。若爾，作用者過去既有，云何得定言唯依現耶？

Citta and caitasika dharmas have the function of grasping the fruit, while form dharmas do not, hence it is called 'half.' If so, since function exists in the past, how can it be definitively stated that it relies only on the present?