俱舍論疏 4.249

4.249

論「不要須說至食水食風」，答也。立一句言，不獲聖法，即是純義。隨獲少多，是雜非純，不名不獲。如說蟬食於風、蚊食於水，即顯蟬唯食風、蚊唯食水，不要須言純食風、水。有人云：如魚食水、如龜食風，以釋純義。不得意也，魚不純食水，龜不純食風故。

[On the] Śāstra['s statement]: "There is no need to say [so] … feeding on water and feeding on wind": This is the answer. Establishing the single phrase 'not acquiring noble dharmas' already conveys the meaning of 'purely'. If one acquires some, whether little or much, that is mixed and not pure, and is not called 'non-acquisition'. Just as saying 'cicadas feed on wind and mosquitoes feed on water' demonstrates that cicadas feed only on wind and mosquitoes feed only on water, without needing to say that they feed 'purely' on wind or water. Some say: 'It is like fish feeding on water and tortoises feeding on wind' to explain the meaning of 'purely'. They have missed the point, for fish do not purely feed on water, nor do tortoises purely feed on wind.