The human individual acquires knowledge primarily by studying the external world, at least initially. This knowledge brings a wealth of perceptions, observations, correlations, inferences, and eventually principles that govern the way the world works. The knowledge may be broken up into various categories and forms, such as physics, chemistry, biology, astronomy, psychology, sociology, engineering, mathematics, art and music, philosophy, etc. but in all cases it is focused on understanding and manipulating the facts of the external life. Sri Aurobindo observes: “There are two kinds of knowledge, that which seeks to understand the apparent phenomenon of existence externally, by an approach from outside, through the intellect,–this is the lower knowledge, the knowledge of the apparent world; secondly, the knowledge which seeks to know the truth of existence from within, in its source and reality, by spiritual realisation.” The world-knowledge uses the senses and the mind to process, organize, define and conclude. Extensions of the world-knowledge occur as we develop ever finer tools to expand our perceptions and test our conclusions, which would include the development of microscopes, telescopes, and all manner of equipment to test what is unseen by the unaided human senses.
Traditionally, those who awaken to the spiritual quest find that they no longer want to simply explore the externalities of life, and they turn their attention to the higher knowledge, the knowledge that comes outside the mental process through a process of identification, and the experience of oneness with a higher level of consciousness. Sri Aurobindo observes that neither form of knowledge can or should be dismissed outright.
“…but in reality they are two sides of one seeking. All knowledge is ultimately the knowledge of God, through himself, through Nature, through her works. Mankind has first to seek this knowledge through the external life; for until its mentality is sufficiently developed, spiritual knowledge is not really possible, and in proportion as it is developed, the possibilities of spiritual knowledge become richer and fuller.”
Sri Aurobindo, The Synthesis of Yoga, Part Two: The Yoga of Integral Knowledge, Chapter 25, The Higher and the Lower Knowledge, pp. 491-492