Meanwhile in Austria, an Austrian physician named Sigmund Freud (1856–1939) was developing his psychoanalytic theory, a work that would span some forty years. Freud will be discussed in detail at various points in this book, but an overview of his theory here is helpful in understanding where psychology went next.

Up to this point in psychology's brief history, most research was focused on the conscious human experience. Freud's theory instead focused on the impact of the unconscious mind, a reservoir of thought, emotions, desires, and feelings that are outside of conscious awareness. You can think of the conscious and unconscious mind like an iceberg. The tip of the iceberg that lies above the surface represents the conscious mind, while the largest part of the iceberg that lies underneath the water represents the unconscious. The unconscious mind often contains thoughts or wishes that are unacceptable or unpleasant, including feelings that are painful, conflicted, or shameful.

The prevailing view in the late nineteenth century was that humans are rational beings, removed from other animals because of logic and morality. To Freud, humans were anything but rational, but were instead driven by selfish “animal” impulses (such as desires for nourishment and sex, and what Freud thought was a built-in aggressive impulse). Freud alleged that these impulses are biological in origin, and they demand satisfaction even though they are part of what he called the unconscious mind. Freud's views were considered hedonistic, suggesting that people exist to seek pleasure and avoid pain — making his theories particularly controversial in Victorian Europe.

So what happens when these impulses are repressed, restrained, or thwarted? According to Freud, it is the denial or suppression of these urges and desires that lead to emotional distress. Along with the fears and guilt over misdeeds — real and imagined — that you accumulate and that become unconscious because they are too painful to think about, they cause people to behave in maladaptive ways. This is especially the case with desires and guilt of a sexual nature, which Freud saw as primary determinants of behavior. Thus, life is a constant struggle to satisfy, or more often to try to contain, your impulses and guilt if you are to give the appearance of being rational and moral and able to live in relative harmony.

Freud developed his theory through his treatment of typically mildly disordered patients, which eventually yielded the treatment approach he called psychoanalysis. Some of Freud's ideas have survived, but much of his theorizing — especially the notion that sex is the primary motivator of human behavior — has been discounted. However, he is still regarded as one of the most influential figures in all of psychology, and he was the first to attempt a comprehensive theory of personality.