The Purpose of Time Travel

CS Lewis began the space trilogy because of an agreement with his friend J.R.R. Tolkien that basically they wanted to write the books they wanted towrite and no one else was writing. So people think that Lewis is basically making up for his friend's failure to complete his end of the bargain, so he put time travel in. But beyond that, as we see there's a purpose to that. And I can't remember if I quote from George Orwell shows up between where we are now and the section I'm looking for. It's around 18 minutes where Gavin describes a heated strength as a weird book.