Its existence depends on the existences of other things, ad infinitum. In other words, there is no permanent, pure element as a basis for the existence of anything. Things exist because of the inter-dependency on one another. This is the basic argument behind 'ontological Emptiness'. On the coarsest level, one can argue that material thing exists only if mind exists first.
Material is thus dependent on mind.
Mind is also dependent on its own self. It should not be too hard to imagine that this core is interacting with the outside world through the brain, and that it is partially conditioned by the brain itself. Empty of all attachments to all dualistic thinkings. In fact, Buddhism asserts that all human's sufferings are due to attachments to dualistic thinking. After all, it is the discriminating mind that tell us that things are impermanent and of suffering nature.