From the author's introduction (italics his):
"Truth is the object of thinking. Some truths are obvious; others are difficult of attainment. Correct thinking is a prime necessity in the solution of complicated problems, and logic enables us to think correctly. Logic is the science of those principles, laws and methods which the mind of man in its thinking must follow for the accurate and secure attainment of truth.

Ordinary man has natural logic or common sense. Scientific logic is natural logic trained and developed to expertness. Logic as a science consists of a comprehensive body of established principles and laws with their legitimate conclusions; logic as an art is the mastery if the technique embodied in these principles and laws.

Ideas, judgments, and inferences are the elements which enter into the operations of the mind in its attainment of truth. Scientific methods are also of importance for this purpose. Hence, logic will treat of ideas, judgments, deductive and inductive inferences. "