Sings Bhagavad Gita:

प्रवृत्तिं च निवृत्तिं च कार्याकार्ये भयाभये
बन्धं मोक्षं च या वेत्ति बुद्धिः सा पार्थ सात्त्विकी
*
pravṛttiṁ ca nivṛttiṁ ca kāryākārye bhayābhaye
bandhaṁ mokṣaṁ ca yā vetti buddhiḥ sā pārtha sāttvikī
*
यया धर्ममधर्मं च कार्यं चाकार्यमेव च
अयथावत्प्रजानाति बुद्धिः सा पार्थ राजसी
*
yayā dharmamadharmaṁ ca kāryaṁ cākāryameva ca
ayathāvatprajānāti buddhiḥ sā pārtha rājasī
*
अधर्मं धर्ममिति या मन्यते तमसावृता
सर्वार्थान्विपरीतांश्च बुद्धिः सा पार्थ तामसी
*
adharmaṁ dharmamiti yā manyate tamasāvṛtā
sarvārthānviparītāṁśca buddhiḥ sā pārtha tāmasī

“That intellect is immaculate, O Parth, which is aware of the essence,
of
the way of inclination as also of renunciation,
of
worthy and unworthy action,
of
fear and fearlessness,
and
of
bondage and liberation.”

In other words, the righteous, morally good intellect is
that
which is aware of the distinction between the way that leads to God
and
the way to recurrent birth and death.

“That intellect is of the nature of passion and moral blindness,
O Parth,
by which one cannot even know the righteous and the unrighteous
as well as
what is worthy or unworthy of being done.”

“That intellect is of the nature of ignorance,
O Parth,
which is enveloped in darkness and which apprehends the sinful as virtuous and
views everything in a distorted way.”

Intellect is graded into three kinds.
The intellect which is well aware of the action that has to be engaged in
and
the action that has to be shunned, as well as of that which is fit or unfit to be done, is
characterized by moral excellence.

The intellect which has only a dim perception of the righteous
and
the unrighteous action,
and
which does not know the truth, is dominated by passion.

The perverse intellect that deems the sinful as virtuous,
the destructible as eternal,
and
the inauspicious as auspicious,
is
shrouded in the gloom of ignorance.

[Revered Swami Adgadanandji]

 As expounded by most Revered Gurudev. 

Humble Wishes!!!