From the moment of birth, humans begin to experience various sufferings. The suffering experienced by infants is mainly hunger, cold, and heat. Usually, they express their needs by crying. As they grow older, during toddlerhood and childhood, they enjoy playing and are curious about nature. They want to observe and try various things. They may like different toys. If they get their favorite toys, they will feel happy; otherwise, they will feel sad. And if their toys are lost or damaged, they will also get upset. During childhood, they are energetic and enjoy hanging out with their peers. Although they have various needs, usually they are easily satisfied and happy. During adolescence, their affection towards the opposite sex grows. Instinctively, they want to date and feel happy while dating. On the contrary, if the person they admire rejects them, they will feel gloomy. After growing up, with the growth of knowledge and abilities, they have more and more desires and hobbies. Some people enjoy arts such as singing, dancing, and acting; some love sports such as martial arts; some like reading and writing; some like traveling; some like to pursue power; while some keep their curiosity and passion for exploring truth. Humans seek happiness and satisfy desires through a wide range of activities. Most humans look for food when hungry, and seek clothing when cold, like other animals. Their lives are about instinctively alleviating suffering and pursuing what they consider to be freedom and happiness. Very few people take the time to ponder what is the root of suffering, what is the essence of happiness, and what is true freedom. Now, let’s delve into these questions.