"Changing of the Guard" is a wonderful story and my very favorite among the many great episodes of the The Twilight Zone. It is sentimental but not in a pretentious sort of way, and has a timeless and universal message for all of us. It is very much a cross between "Goodbye, Mr. Chips" and "It's a Wonderful Life".
Donald Pleasance plays the kindly old Professor Fowler, a teacher of poetry at an all-boys prep school in Vermont. His sudden, forced retirement after more than fifty years at the school leads him to doubt the value of his teachings and, by extension, his life. In despair and feeling that he has been a failure, he visits the school on a winter's night prepared to take his own life. What happens next is one of the most touching and uplifting scenes ever produced by Mr. Serling and company.
If there is a subtext to this episode, it is one that perhaps speaks more urgently today than it would have in 1962, when this episode was filmed; that is the true and essential value of reading literature. In today's vocationally-driven academic world, where the humanities are increasingly de-valued and technology has been placed upon an altar, it's hard to imagine a time when poetry would have been placed alongside mathematics and science as a subject worthy of serious study. Fowler's victory in this story is a victory for everyone who recognizes the essential importance of literature and, in today's world, sees the cultural and sociological consequences of ignoring it.