You do not know how to train the totality of the mind and the different functions of the mind. A vast part of the mind remains buried in the unknown. Patanjali makes you aware of your mind first, because it is mind, both conscious and unconscious, its various aspects and functions, and all its vrittis or modifications that create a wall between you and Reality.
The second sutra explains the aim of the entire yoga psychology. “Yogash chitta-vritti-nirodhah.” There are two meanings for this. By applying the yogic methods that are being explained to you by your teacher, you can have control over mind and its modifications, and thus attain samadhi, the highest state of wisdom; this is one meaning. Having control over mind and its modifications is called yoga; this is the second meaning.
The word yoga has many connotations, but here it means “samadhi.” The word “yoga” comes from the root “yuj,” and it means “to unite, to join.” When prana and apana are joined, that is called yoga. When an individual soul is united with the cosmic soul, that is called yoga. When one attains samadhi, that is also called yoga. The aim and object of yoga is to attain the highest of all states—samadhi. Patanjali is not talking about seeing God; whether or not God exists is not the point of Patanjali. He says, “Oh man, you have to know yourself on all levels.” First, you have to understand yourself on all levels, and then you can understand the Self of all, the Absolute Self, that is called Absolute Truth.