The idea of freedom is not an illusion, it comes from the very depths of our being, never from reason. Lower reason can only end in skepticism, because what is ordinarily called reason, can never take us to the truth; but the higher reason, the purified reason, can reveal the truth to us. It is not Kant’s reason, but the highest intuitive vision that reveals the Truth directly.
Vedantic treatises such as the Drig Drishya Viveka are
concerned with the task of developing that higher reason in us. Ours is gross
reason, but that reason can be made finer and finer by going through a process of
steady, prolonged purification and strict ethical culture in thought, word and
deed. Philosophy is not mere empty speculation with no bearing on life. It is
the pursuit of knowledge that reveals the Truth to us directly. When a person
is emancipated from all bonds, when lust no longer finds any place in his mind,
and when he has become truthful in character, then he attains Brahman.
In both Yoga and Advaita Vedanta, very great stress is laid
on clear thinking, on not identifying oneself with the non-self, with the
phenomenon. When the modifications of the mind are controlled, the Self ceases
to identify Itself with the non-self, or the phenomenon. Even what is called
samadhi clarifies the understanding, the discriminative faculty. When a man
comes down from samadhi he should be able to separate the Self from the
non-self.
Source - Swami Yatiswarananda, How to Seek God, 194–5