the reality that we accept is for us at any time the simplest description of the phenomena as known to us. To put this view in our own way, we might say that the world is scientifically viewed as a perfectly united whole, which would, if fully known, fully satisfy our highest mental desire for continuity and perfect regularity of conception. Therefore it is that the “universal formula” of the last chapter is a conception that expresses the scientific ideal. With less perfection, harmony, and unity of thought about the world, science will never rest content so long as she continues to be science. But for this very reason science postulates that this perfect order must be already realized in the world. It is not merely that this order is the practically unattainable but still necessary ideal for our reason; but we must postulate that this order is already present in things, far off as our thought is from it. This postulate gives life to our scientific thought. Without it our search for an order that need not exist is meaningless play.
This postulated order, however, if found, would mean for us relative simplicity and economy of conception. The infinite mass of phenomena would be conceived as one whole. The maximum of wealth of facts would be grasped with the minimum of mental effort. We postulate after this fashion that the world loves parsimony, even as we do.
To illustrate by the case of one science. A great master of mechanical science has called it the science which gives the simplest possible description of the motions in the world. If we accept this account of
