Things, or objects, change their properties: a banana is green one day and some days later it is yellow; a kettle is hot at one time and some time later it is cold; a person is bent at the times when he or she is sitting and straight at the times when he or she is standing. How can a banana be both green and yellow all over? By being green and yellow at different times, of course, since for something to change it must have incompatible properties at different times.1 But how is change possible? Given that certain properties cannot be had at the same time, why is it possible to have them at different times? Why and how does a difference in time make possible what is otherwise impossible? Why is it not a contradiction that a banana is green and yellow, i.e. not green, all over at different times? This is the problem of change, and several solutions have been proposed.