The Principles of Psychology

What it is

The Principles of Psychology is an 1890 book by William James, published in two volumes by Henry Holt and Company in New York. James, who had trained as a physician before turning to psychology, wrote it over twelve years while teaching at Harvard University.

Why it matters

The book summarized the whole field of psychology as it stood in 1890 and helped establish psychology as a credible science in the United States. It introduced ideas still taught today: the mind as a continuous 'stream of consciousness', the James–Lange theory that bodily reactions produce emotions, and the power and difficulty of changing habits. It reveals James as both a careful scientific observer and a writer concerned with deeply personal questions, including free will.

Look closer

• Why might James have worried about the book's great length, as he says in his preface?
• How does describing thought as a 'stream' change the way we imagine the mind, compared to a 'chain' of ideas?
• What does the title page tell you about who the book was written for?