Because it asserts that there is consciousness-only (vijñapti-mātratā), the difficulty in philosophically approaching the Yogācāra-Buddhist text Cheng weishi lun centers on the problem of the external world. This paper is based on a review by Lambert Schmithausen that, specifically with regard to the problem of the external world, questions Dan Lusthaus’s phenomenological investigation of the CWSL. In it I point out that the fundamental temporality of consciousness brought to light by the Yogacaric revelation of the incessant differentiation of consciousness (vijñāna-pariṇāma) calls into question every temporally conditioned, and hence appropriational, understanding of vijñapti-mātratā. Therefore, the problem of the external world cannot be approached without taking into account the temporality of consciousness, which, furthermore, compels us to face the riddle of time