Interestingly it was on Lewis’s fifty-sixth birthday (in 1954) that he gave what hard-core enthusiasts of his works often consider one of his best talks to a non-religious audience. “De Descriptione Temporum” are not words you hear every day, but they were fitting as a title for his inaugural lecture as Professor of Medieval and Renaissance English Literature at Cambridge University. The translation for this Latin title is “a description of the times.” The Internet Archive has a copy of the complete text. Later it was recorded (4/1/1955) as a radio broadcast for the BBC where the title was “The Great Divide” and aired on April 6, 1955. You can get a copy of this recording, along with other audio featuring his voice from Episcopal Marketplace.
As you might imagine, there are differences between the radio version and the actual address. If you have both you will want to listen to it and follow along the printed version to see Lewis’s ability to adapt a text to different audiences.