What and that are two incompatible directions of measurement which apply to the unchanging mystery of presence. The thing, the cause, la chose, is constant outside of all experience but the apparatus which realises it can take these two directions, call them essence and being: I am what I am, or I am that I am. It rarely or never happens that you find yourself in a pure state, but if you are most clearly what you are, what you happen to be, then your being is smeared out over the broadest scope of the world, and if you draw close to realising the pure event of being then what you are is scattered over all possibilities. It is the indeterminacy of these categories that makes for the unresolvable displacement at the heart of your experience of yourself, at the same time as you know yourself to be one beyond all sense of personal identity and necessarily without being able to encompass or express this oneness in any way. The mystery is not really a mystery at all, it's only that the categories by which you actualise contain this strange incompatibility which itself follows from their absolute efficiency.