People are learning and gaining knowledge throughout their entire life, from the very beginning " until the end. From the first day in this world, human being is exposed to different stimuli, objects, other people and even inner experience which included people's thoughts, feelings and sensations. Inner experience is how they feel about something. These experience is shaped by people's existence. Some people prefer learning from books, whereas other maintain that first-hand experience provides a better learning experience. What's more, books cannot fully replace worldliness but can increase, simplify and speed up the process of gaining knowledge. .

             Certainly, first-hand experience is useful to learn about different field of the life, but can be also less efficient or not available everywhere. Whereas books are comparatively cheap, easy available and can be used anywhere. For example, people can learn who Celts were only by reading books about them, written by specialists in a particular area. In this case it is almost impossible to acquire some knowledge about Celts and their lives in other way, as not everybody can take part in archaeological excavations, unless you are specially educated to do so. Without books and only with personal experience the number of people having access to knowledge would be seriously limited. .

             On the other hand, it would be more time-saving and efficient to attain awareness from other people as well as from personal experience. There are many things that we cannot learn from books and should learn by ourselves. Marxists claimed that "man's social practice alone is the criterion of the truth of his knowledge of the external world." For example, before Nicolaus Copernicus proved by his heliocentric model of the universe that the earth is spherical, everybody believed that the earth is flat. The reason for it was the fact that nobody circumnavigate the world, believing that somewhere has to be an end of the earth.