A philosophical essay leaves much to the reader, often saying too little for fear of saying too much; its attention is concentrated, but it does not stay to cross all the ts of the argument; its mood is cautious without being defensive; it is personal but never merely 'subjective'; it does not dissemble the conditionality of the conclusions it throws up and although it may enlighten it does not instruct. It is, in short, a well-considered intellectual adventure recollected in tranquility.