Metaphysics of Presence

I keep wondering what this is. I have thought that it was as of something a lecturer said which was something like for something to exist something needs not to exist or be true. Also that this way of thinking has influenced us from the time of the Greeks. Other ways of thinking can include both aspects of a polarity has having existence or validity. For examply this can include Post Modern ideas or maybe some eastern ideas of non dualism. For a while I was under the assumption that the metaphysics of prescence was associated with Aristotle but recently I have been reading an association with Heidegger. Perhaps I should just research it thoroughly once and for all and find out.