Time is just a coordinate, in relativity theory. The time coordinate has an opposite sign to the space coordinates, and that subtle difference is responsible for all of the enormous apparent difference between space and time.
Granted, relativity theory is not a complete and accurate specification of the world in which we live (that requires QM to be incorporated), but it is still a self-consistent model which illustrates how time can be dealt with mathematically in a uniform way with space. Time and space are not fundamentally different in relativity; they shade into one another and can even change places entirely, if you cross the event horizon of a black hole. In fact, one can construct models in which there are more than one dimension of time, just as we have more than one dimension of space. How would your renaissance philosphers deal with two dimensions of time? I think their ideas are obsolete and have no reference or value given our much deeper modern understanding of these issues. Hal Finney
