Let us strip it [the relativist contention] of the illegitimate emotional power it derives from the word ‘stagnation’ with its suggestion of puddles and mantled pools. If water stands too long it stinks. To infer thence that whatever stands long must be unwholesome is to be the victim of metaphor. Space does not stink because it has preserved its three dimensions from the beginning. The square on the hypotenuse has not gone moldy by continuing to equal the sum of the squares on the other two sides. Love is not dishonored by constancy, and when we wash our hands we are seeking stagnation and “putting the clock back,” artificially restoring our hands to the status quo in which they began the day and resisting the natural trend of events which would increase their dirtiness steadily from our birth to our death. For the emotive term ‘stagnant’ let us substitute the descriptive term ‘permanent.’ Does a permanent moral standard preclude progress? On the contrary, except on the supposition of a changeless standard, progress is impossible. If good is a fixed point, it is at least possible that we should get nearer and nearer to it; but if the terminus is as mobile as the train, how can the train progress towards it? Our ideas of the good may change, but they cannot change either for the better or the worse if there is no absolute and immutable good to which they can recede. We can go on getting a sum more and more nearly right only if the one perfectly right is “stagnant”.
— C.S. Lewis, “The Poison of Subjectivism”