Knowledge of the physical world leads you to the knowledge of something non- physical, transcendental. Knowledge is a continuous expansion of awareness of reality. At first, it is a surface reality and later, a deeper reality. First, you know yourself as a body, then you get the deeper knowledge of yourself as a soul. Secular and sacred are both part of God. All knowledge is sacred. Because, the universe is nothing but the expression of the Divine. That is the first utterance in the Ishopanishad. When you see through to the very heart of things. You find nothing but God. On the surface level, you see molecules, atoms etc., but when you go deep, there is nothing but Pure Consciousness, the essence of everything that is the Atman, that is Brahman- the words used in the Upanishads.