our pope is a great admirer (and subscriber) of the particular branch of existentialism called ‘phenomenology’, which is a study of our EXPERIENCE of the world around us. kierkegaard is the father of existentialism, which is a philosophy that emphasizes the role of our experience of the world around us, and some people take this philosophy to an extreme, resulting in solipsism.
phenomenology can be contrasted to the idea of ontology, which is the study of what is actually, in reality, happening around us (coming from a greek word for being).
an example might be the eucharist. what we experience, the phenomenology of the moment, would be consumption of bread and wine. if we believe that it is the body and blood of Christ, then the ‘doxism’ (belief system) of our faith would be involved in the phenomenology of the act, and transubstantiation would be part of our experience.
however, if you look at the same event ontologically, then you see that it really IS the body and blood of Christ, whether we believe it is or not. there is a fundamental change in the essence of the bread and wine, and they do in fact become Him, whether we believe it, or even know about it, or not.
does that make sense?