The five human senses are described as five horses and the mind as a chariot.
The ancients knew that if a charioteer had no knowledge and was incapable of eliminating what was not good and making a distinction between right and wrong (this is called Viveka), each of the five horses would be towed to their side.
Instead of unification and harmony, this inability to make differences leads to even deeper separation.
So, hence the ancients knew that ignorance hurts.
The second chapter of the Yoga Sutra explains nature and causes of obstacles and how to eliminate them.
The third chapter defines the higher concentration, the synthesis of the previous practices and the result, explains the concept of time, how to apply the highest experience and the results which lead to the perfection of the recognition. Every recognition leads to a higher ones. These are the powers of the higher stages of Yoga and theirs practice. Those are:
Dharana or concentration,
Dhyana or meditation and
Samadhi, which is self-realization, which is the same as self-knowledge or knowledge of the Self.
When the time is ripe, one finds himself on the stages of that higher Yoga without much effort. These three high stages of Yoga, concentration, meditation and samadhi narrow the mind, where “narrowing of the mind” leads to great depth of heart and not to endless suffering caused by deepest ignorance.
Basically, there is no difference between these three high states of Yoga and consciousness. These states are rather different degrees of transformation.
Practicing concentration and meditation can awaken the greatest potential of the brain.