The Little Schemer is fundamentally a book about reasoning using recursive logic. It uses the language, Scheme (a Lisp dialect), as a medium. It starts very simple, slowly acquainting the reader to thinking in terms of recursion, building more and more complex functions. By the final chapters, the authors begin to introduce ideas very fundamental to computer science such as the Y-combinator and the Halting problem.
Abstract theory aside, the book has practical benefits as well. Solving programming problems using only recursion (without for and while loops) forces the reader to think differently about problems than how they would normally think about them in day-to-day work. I found the challenge of working within the constraints of Scheme to be a lot of fun!
Scheme is made up of atoms and lists. Atoms and lists, together, are called S-expressions. Atoms are simple strings or digits (e.g., a, cat, 123). Lists are S-expressions with a pair of parentheses containing a