From anger, complete delusion arises, and from delusion bewilderment of memory. When memory is bewildered, intelligence is lost, and when intelligence is lost one falls down again into the material pool.
Śrīla Rūpa Gosvāmī has given us this direction:
prāpañcikatayā buddhyā
hari-sambandhi-vastunaḥ
mumukṣubhiḥ parityāgo
vairāgyaṁ phalgu kathyate
(Bhakti-rasāmṛta-sindhu 1.2.258)
By development of Kṛṣṇa consciousness one can know that everything has its use in the service of the Lord. Those who are without knowledge of Kṛṣṇa consciousness artificially try to avoid material objects, and as a result, although they desire liberation from material bondage, they do not attain to the perfect stage of renunciation. Their so-called renunciation is called phalgu, or less important.
(Bhagavad-Gita-----2:63-----translation and purport).

According to Bhakti-rasāmṛta-sindhu (1.4.15-16), the science of devotional service:
ādau śraddhā tataḥ sādhu-
saṅgo 'tha bhajana-kriyā
tato 'nartha-nivṛttiḥ syāt
tato niṣṭhā rucis tataḥ
athāsaktis tato bhāvas
tataḥ premābhyudañcati
sādhakānām ayaṁ premṇaḥ
prādurbhāve bhavet kramaḥ
"In the beginning one must have a preliminary desire for self-realization. This will bring one to the stage of trying to associate with persons who are spiritually elevated. In the next stage one becomes initiated by an elevated spiritual master, and under his instruction the neophyte devotee begins the process of devotional service. By execution of devotional service under the guidance of the spiritual master, one becomes free from all material attachment, attains steadiness in self-realization, and acquires a taste for hearing about the Absolute Personality of Godhead, Śrī Kṛṣṇa.
(Bhagavad-Gita-----4:10-----purport).

When one acts in Kṛṣṇa consciousness for the satisfaction of the senses of Kṛṣṇa, any action, whether of the body, mind, intelligence or even the senses, is purified of material contamination. There are no material reactions resulting from the activities of a Kṛṣṇa conscious person. Therefore purified activities, which are generally called sad-ācāra, can be easily performed by acting in Kṛṣṇa consciousness. Śrī Rūpa Gosvāmī in his Bhakti-rasāmṛta-sindhu (1.2.187) describes this as follows:
īhā yasya harer dāsye
karmaṇā manasā girā
nikhilāsv apy avasthāsu
jīvan-muktaḥ sa ucyate
"A person acting in Kṛṣṇa consciousness (or, in other words, in the service of Kṛṣṇa) with his body, mind, intelligence and words is a liberated person even within the material world, although he may be engaged in many so-called material activities." He has no false ego, for he does not believe that he is this material body, or that he possesses the body. He knows that he is not this body and that this body does not belong to him. He himself belongs to Kṛṣṇa, and the body too belongs to Kṛṣṇa. When he applies everything produced of the body, mind, intelligence, words, life, wealth, etc.—whatever he may have within his possession—to Kṛṣṇa's service, he is at once dovetailed with Kṛṣṇa. He is one with Kṛṣṇa and is devoid of the false ego that leads one to believe that he is the body, etc. This is the perfect stage of Kṛṣṇa consciousness.
(Bhagavad-Gita-----5:11-----purport).

"No one can understand the transcendental nature of the name, form, quality and pastimes of Śrī Kṛṣṇa through his materially contaminated senses. Only when one becomes spiritually saturated by transcendental service to the Lord are the transcendental name, form, quality and pastimes of the Lord revealed to him." (Bhakti-rasāmṛta-sindhu 1.2.234)
This Bhagavad-gītā is the science of Kṛṣṇa consciousness. No one can become Kṛṣṇa conscious simply by mundane scholarship. One must be fortunate enough to associate with a person who is in pure consciousness. A Kṛṣṇa conscious person has realized knowledge, by the grace of Kṛṣṇa, because he is satisfied with pure devotional service. By realized knowledge, one becomes perfect. By transcendental knowledge one can remain steady in his convictions, but by mere academic knowledge one can be easily deluded and confused by apparent contradictions. It is the realized soul who is actually self-controlled, because he is surrendered to Kṛṣṇa. He is transcendental because he has nothing to do with mundane scholarship. For him mundane scholarship and mental speculation, which may be as good as gold to others, are of no greater value than pebbles or stones.
(Bhagavad-Gita-----6:8-----purport).

"When one is not attached to anything, but at the same time accepts everything in relation to Kṛṣṇa, one is rightly situated above possessiveness. On the other hand, one who rejects everything without knowledge of its relationship to Kṛṣṇa is not as complete in his renunciation." (Bhakti-rasāmṛta-sindhu 1.2.255-256)
A Kṛṣṇa conscious person well knows that everything belongs to Kṛṣṇa, and thus he is always free from feelings of personal possession. As such, he has no hankering for anything on his own personal account. He knows how to accept things in favor of Kṛṣṇa consciousness and how to reject things unfavorable to Kṛṣṇa consciousness. He is always aloof from material things because he is always transcendental, and he is always alone, having nothing to do with persons not in Kṛṣṇa consciousness. Therefore a person in Kṛṣṇa consciousness is the perfect yogī.
(Bhagavad-Gita-----6:10-----purport).

A yogī who is practicing meditation on the Supersoul sees within himself the plenary portion of Kṛṣṇa as Viṣṇu—with four hands, holding conchshell, wheel, club and lotus flower. The yogī should know that Viṣṇu is not different from Kṛṣṇa. Kṛṣṇa in this form of Supersoul is situated in everyone's heart. Furthermore, there is no difference between the innumerable Supersouls present in the innumerable hearts of living entities. Nor is there a difference between a Kṛṣṇa conscious person always engaged in the transcendental loving service of Kṛṣṇa and a perfect yogī engaged in meditation on the Supersoul. The yogī in Kṛṣṇa consciousness—even though he may be engaged in various activities while in material existence—remains always situated in Kṛṣṇa. This is confirmed in the Bhakti-rasāmṛta-sindhu (1.2.187) of Śrīla Rūpa Gosvāmī: nikhilāsv apy avasthāsu jīvan-muktaḥ sa ucyate. A devotee of the Lord, always acting in Kṛṣṇa consciousness, is automatically liberated.
(Bhagavad-Gita-----6:31-----purport).

Kṛṣṇa is the Supreme Personality of Godhead, the cause of all causes, the primeval Lord Govinda. Īśvaraḥ paramaḥ kṛṣṇaḥ sac-cid-ānanda-vigrahaḥ/ anādir ādir govindaḥ sarva-kāraṇa-kāraṇam. It is very difficult for the nondevotees to know Him. Although nondevotees declare that the path of bhakti, or devotional service, is very easy, they cannot practice it. If the path of bhakti is so easy, as the nondevotee class of men proclaim, then why do they take up the difficult path? Actually the path of bhakti is not easy. The so-called path of bhakti practiced by unauthorized persons without knowledge of bhakti may be easy, but when it is practiced factually according to the rules and regulations, the speculative scholars and philosophers fall away from the path. Śrīla Rūpa Gosvāmī writes in his Bhakti-rasāmṛta-sindhu (1.2.101):
śruti-smṛti-purāṇādi-
pañcarātra-vidhiṁ vinā
aikāntikī harer bhaktir
utpātāyaiva kalpate
"Devotional service of the Lord that ignores the authorized Vedic literatures like the Upaniṣads, Purāṇas and Nārada Pañcarātra is simply an unnecessary disturbance in society."
(Bhagavad-Gita-----7:3-----purport).