You may read in this book descriptions of theories that were the first of their kind in the history of thought. Undoubtedly, the conclusions reached by philosophers may seem obvious to us now, but if we look back through the rearview mirror, we will see that these were ideas and theories that were completely new at the time. Although their answers are clear and simple, if we examine them, we will find that they were not easy at the time. Theories and ideas that seem contradictory or self-evident are ideas that can make us question our perceptions of ourselves and the world around us—ideas that can make us question and consider other paths and new paths.

The importance of philosophical ideas stems from their spread beyond the realm of philosophy as well. That is, philosophy has entered not only the realm of science, but also the laws of society, principles of ethics, and moral values. Some philosophical ideas have given us the basis for traditional knowledge and led to the beginning and foundation of political and artistic movements and organizations. The relationship between science and philosophy has often been one of mutual stimulation, each enriching the other and giving new life to each. There is an entire branch of philosophy that studies the ideas, methods, and techniques of science and knowledge. From this, logical thinking grew and flourished, influenced the development of mathematics, and became the basis of the scientific method, which relies on systematic observation and monitoring to explain and interpret the world. Ideas primarily related to the consciousness of the individual, which speak of perception, diagnostic awareness, and what it is to be human, evolved into psychology and psychoanalysis.