how does karma yoga leads us to the path of knowledge ?
The very best answers you can find to your deep question of: How does karma yoga lead us to the path of knowledge? — can be found in two books, The Essence of the Bhagavad Gita Explained by Paramhansa Yogananda, as remembered by his disciple, Swami Kriyananda, and The Art and Science of Raja Yoga by Swami Kriyananda. Both are available from www.crystalclarity.com. They are also available in India from www.anandaindia.org.
Your question is very brief and philosophical, so I am going to take a guess that you are perhaps faced with the necessity of doing a lot of outward work in your life and are wondering how, or if, this can lead you to your goal of greater knowledge. This is a common dilemma in our world.
The essence of karma yoga is to discover through meditation the calmness within and to take that into your daily service, feeling that God is the Doer in all things. Cultivate an attitude of joyfully and willingly offering your energy to God in grateful service. Our masters tell us that Man is under obligation to render grateful service for the free gift of iife. When faced with challenges or pressures, try to offer these to God and attune yourself to His guidance as to what is best.
In divine friendship,