"The choice (or accident) of s creates a sense of time directionality in a physical environment. The 'arrow' of entropy increase is a reflection of the improbability of those initial conditions which are entropy-decreasing in a closed physical system. ... Everywhere... in the Universe, we discern that closed physical systems evolve in the same sense from ordered states towards a state of complete disorder called . This cannot be a consequence of known laws of change, since... these laws are time symmetric—they permit... time-reverse... The initial conditions play a decisive role in endowing the world with its sense of temporal direction. ...some prescription for initial conditions is crucial if we are to understand... A Theory of Everything needs to be complemented by some such independent prescription which appeals to simplicity, economy, or some other equally metaphysical notion to underpin its credibility. The only radically different alternative... a belief that the type of mathematical description of Nature... —that of causal equations with starting conditions—is just an artefact of our own preferred categories of thought and merely an approximation... At a deeper level, a sharp divide between those aspects of reality that we habitually call 'laws' and... 'initial conditions' may simply not exist."