This book contains a series of lectures held between 1975 and 1977.
The fundamental thesis is that human brains are designed by nature to work with other brains: the most important task of a brain is to react to other brains. The whole pattern of growth and behavior is based on socialization. Young emphasizes that human brains are designed to recognize features of human beings (speech, facial expressions).
The metaphor that Young uses to explore this thesis is that the life of a human being is regulated by four programs, each written in a specific language: the genetic program (written in the language of DNA), the neural program (written in the language of neurons and their connections), the linguistic program (written in the natural languages that we speak), and the recording program (written in the language of the media that we use to record our knowledge for future generations).
Young points to a fundamental property of life: the ability to make choices. Living beings use the available information to make choices, according to the instructions of their genetic program, with the purpose of surviving and reproducing. The genetic program itself represents a gigantic sequence of past choices made over millions of years.
Even at the smallest level, the level of the cell, choice is the fundamental activity: the cell chooses among the possible actions the one that is compatible with the instructions coded in its DNA. The choice has been determined by natural selection over millions of years.
More complex forms of life simply make more complex choices, but the ultimate mechanism is the same at all levels.
Young believes that learning is largely a matter of "selecting" pathways that are already present in the brain. The neural program is due to the interaction between the genetic program and the environment. This interaction causes the selection of some over other possible pathways. Basically, this interaction creates the "instructions" of the neural program, that will then guide behavior. The behavior of a living being is thus both the outcome of genetic instructions and a reflection of the environment in which the living being lives.
Young discusses the biological clocks that govern the rhythms of our lives, from breathing to reproducing. They are programs of the brain that keep us alive and allow us to interact with the world.
He then explores the programs at higher levels of behavior, from seeing to loving to warfare to art. Art, for example, serves the purpose of creating symbols, one of the fundamental features of our brains. Religion is a symbol of the interaction of the individual with society and the world.
Young argues (unconvincingly) in favor of free will and even vitalism.