1in the winter of 925, the University of Marburg nominated Heidegger as its professor, but the Ministry of Education did not approve it, on the grounds that he had not published his official works. Therefore, Heidegger wrote, sorted out and published the mature part of his thinking about existence for many years. This is the epoch-making philosophical masterpiece of the 20th century that made Heidegger famous-Being and Time. In this book, Heidegger systematically expounds the question of what existence is and the relationship between existence and time. When this book was published, it had more than 400,000 words, but only 1/3 of the original writing plan. For various reasons, the latter part is not added. However, Heidegger claimed that some of his later published research results have basically shown the whole picture of his philosophical thoughts.