There were six schools of दर्शन (darshana). Darshana is a philosophical system and these six were samkhya, yoga, nyaya, vaisheshika, mimamsa and vedanta. Nyaya is about logic and epistemology. The epistemology bit gives us four acceptable methods of proof (प्रमाण, pramana) or means of knowledge. (A word of caution, the nomenclature and acceptability varies across texts.) These four are प्रत्यक्ष (pratyaksha) or direct perception, अनुमान (anumana) or inference, उपमान (upamana) or comparison/analogy and शब्द (shabda) or verbal authority or evidence of acceptable experts. I don't buy the simplistic antithetical portrayal of science versus the metaphysical/spiritual (I am deliberately not using the word religion) and the assumption that science is based on the empirical, while the metaphysical is based on faith. Mount Everest is the tallest mountain on earth. The acceleration due to gravity is 32 feet per second per second. Most of us (I don't know about all) believe in such propositions. Are they based on our direct perception? No, they are based on shabda. Let's not accept that everything we believe in is based on pratyaksha. You will instantly produce a counter-argument. True, such propositions are based on shabda. But should we so wish, we can subject them to the pratyaksha test. We can replicate the Radhanath Sikdar and Galileo/Newton experiments. Indeed, but metaphysical/spiritual is also about the empirical. Swami Vivekananda wrote/said this several times. Here is one quote, from the monograph Raja Yoga: 'All our knowledge is based upon experience. What we call inferential knowledge, in which we go from the less to the more general, or from the general to the particular, has experience as its basis. In what are called the exact sciences, people easily find the truth, because it appeals to the particular experiences of every human being… The Christian asks you to believe in his religion, to believe in Christ and to believe in him as the incarnation of God, to believe in a God, in a soul, and in a better state of that soul. If I ask him for reason, he says he believes in them. But if you go to the fountain-head of Christianity, you will find that it is based upon experience. Christ said he saw God; the disciples said they felt God; and so forth. Similarly, in Buddhism, it is Buddha's experience. He experienced certain truths, saw them, came in contact with them, and preached them to the world. So with the Hindus. In their books the writers, who are called Rishis, or sages, declare they experienced certain truths, and these they preach. Thus it is clear that all the religions of the world have been built upon that one universal and adamantine foundation of all our knowledge—direct experience.'

senses

Nothing Is for Your Eyes Only

Smelling a Sight, Hearing a Look