Nyaya, which is a school of Indian philosophy, focuses on the methods of attaining knowledge through logic and epistemology. The word "Nyaya" means "logic" in Sanskrit, and this school of thought is based on the belief that knowledge is the key to liberation from suffering. In Nyaya, there are four main methods used to attain knowledge, which are perception, inference, comparison, and testimony.

The first method, perception, is considered to be the primary means of acquiring knowledge in Nyaya. Perception is defined as the direct awareness of an object through the senses. This means that knowledge is gained through the experience of the external world, and it is considered to be the most reliable source of knowledge. In Nyaya, perception is divided into two types: direct perception and indirect perception. Direct perception refers to the immediate awareness of an object through the senses, while indirect perception refers to the inference of an object based on its effects or signs.

The second method, inference, is based on the principle of cause and effect. In Nyaya, inference is defined as the process of arriving at a conclusion based on a known fact or observation. This method is used to gain knowledge about things that are not directly perceived, such as the existence of air or the presence of fire in a distant place. Inference is considered to be a reliable method of attaining knowledge, as long as it is based on valid premises and follows a logical process.

The third method, comparison, is used to gain knowledge by comparing objects or concepts. This method involves the analysis and evaluation of similarities and differences between two or more objects. By comparing different objects, one can gain a deeper understanding of their qualities and characteristics. This method is particularly useful in gaining knowledge about abstract concepts, such as the nature of the self or the concept of time.

The final method, testimony, refers to the knowledge gained through the words of others. In Nyaya, testimony is considered to be a valid source of knowledge, as long as the person giving the testimony is reliable and trustworthy. This method is often used in the context of spiritual or religious teachings, where knowledge is passed down through generations through oral tradition.

In conclusion, Nyaya employs a variety of methods to attain knowledge, including perception, inference, comparison, and testimony. These methods are based on the belief that knowledge is the key to understanding the world and achieving liberation from suffering. By combining logic and epistemology, Nyaya provides a comprehensive approach to gaining knowledge and understanding the nature of reality.