While the Vaibhāṣikas held that dharmas of the three times all exist, they held that only present dharmas have "efficacy" ("karitra"), thus they were able to explain how the present seems to function differently than the past or future. Among the different Sarvāstivāda thinkers, there were different ideas on how this theory was to be understood. These differences were accepted as long as they did not contradict the doctrine of "all exists" and can be seen in the MVŚ, which outlines the four different interpretations of this doctrine by the ‘four great Ābhidharmikas of the Sarvāstivāda’: Dharmatrāta, Buddhadeva, Vasumitra and Ghoṣaka.