The purpose of this paper is to argue that the infinitival and participial complements of perception verbs and causative verb have, as in (1) and (2), derive from a common sentential complement and that the contrast between the infinitival and participial complements is one of nonprogressive vs. progressive aspect. (1) a. I saw the moon rise over the mountain. b. I saw the moon rising over the mountain. (2) a. He had his students do a survey of voting behavior. b. He had his students doing a survey of voting behavior. In Section 1, I present a number of arguments in support of the analysis in which the above four complements come from a null-comple-mentiaer S as in (3), i.e. an analysis similar to the one which Chomsky assigns to sente...