Whilst CS Lewis may be best known for his childrens' fiction, such as the Chronicles of Narnia, some of his other works are well worth a read.
This volume of essays is a good place to start. Each essay is short and to the point, resulting in 'bite-sized Lewis', as it were.
The book is organised into several different thematic chapters, but perhaps the most interesting essays are to be found in Chapter 2: The Art of Writing and the Gifts of Writers. Here Lewis sets forth his views on why fantasy and fairytale is helpful to a developing child, and his views on his sometime friend J.R.R. Tolkien's writings.
Lewis was no stranger to literary criticism, and many of the essays are written in response to articles or reviews. Even today, Lewis is remains a controversial figure. Archbishop Rowan Williams has written, "...the problem is less, I think, with Lewis's method than with his unmistakeable clumsiness in handling a good many contemporary aspects of the world in plausible fictional terms." (Williams, 2000). This book goes beyond the fiction and fairytales, and finds Lewis attempting to debunk intellectual moral self deception wherever he finds it.