Why is it said that the Mind is the cause of all misery and the means to freedom too

Verily, the mind is creation (jagat) itself; it is all the world for the individual. While in deep sleep, the mind doesn’t function, so creation is practically non-existent for the individual. Creation is born (or “enters into the consciousness”) and dies (or “disappears from the consciousness”) according to the cognitive powers of the mind. Therefore, when the mind is destroyed, the world is also destroyed and one is free, one is liberated, one attains moksha. Whoever succeeds in controlling the consciousness (Chitta) can have a vision of the Atma. Consciousness is the grown-up tree, while the seed is the “ego”, the feeling of “I”. When the seed “I” is cast aside, all the activities of the consciousness also vanish automatically. The spiritual aspirant who is earnest for these results has to be ever vigilant. At any moment, the senses might regain their lost mastery and enslave the individual.

– Jnana Vahini, Ch 7.