What is this book about?

This book is fundamentally about dissecting and understanding the building blocks of English sentences. Clark moves beyond simple lists of parts of speech to introduce formal grammatical categories like 'phrase' and 'clause'. He proposes a hierarchical structure for sentences, often represented in a tree-like diagram (phrase structure), showing how smaller units combine to form larger ones. The book systematically analyzes various sentence types (declarative, interrogative, imperative) and examines relationships between words, movement phenomena (like questions and negatives), and the grammatical functions of pronouns.