What is vital and healthy does not necessarily survive. Higher organisms are often conquered by lower ones. Arts as well as men are subject to accident and violent death. The philosophy of history outlined by Keats's Oceanus is not true. We ask too often why cultures perish and too seldom why they survive; as though their conservation were the normal and obvious fact and their death the abnormality for which special causes must be found. It is not so. An art, a whole civilization, may at any time slip through men's fingers in a very few years and be gone beyond recovery. If we are alive when such a thing is happening we shall hardly notice it until too late; and it is most unlikely that we shall know its cause.[C. S. Lewis, English Literature in the Sixteenth Century (Excluding Drama), HarperCollins (New York: 2022) pp. 133-134.]
In context, Lewis is discussing the sudden and calamitous collapse of Scottish poetry at the end of the late Middle Ages, as it went from being a thriving. skilled, and creative tradition in Middle Scots to a fragmented, highly derivative, and imitative field in which Scottish poets regularly apologized for writing in Scots rather than English. But he is also deliberately drawing a more general moral.
