 Lewis considers three answers to this question. According to the first for some object O to be F at t is for the relation of being F to tenselessly, or timelessly, hold between O and time t. For example, for Plate to be round at t1 is for the two-place relation of being round at to hold between Plate and t1. Something can stand in the relation of being round at to the earlier time t1 without standing in that relation to the later time t2. So there is no reason to think that standing in the relation of being round at to t1 is incompatible with standing in the relation of being square at to t2. By transmuting the ostensibly one place relational properties of being round and being square into the two place relational properties of being round at and being square at we can show how something can be round at one time and square at another.