1.) June 7 1968 letter Gargamuni
For serving the Lord, we require to sacrifice our life, our wealth, our intelligence, and our words. One can serve the Lord with these four possessions; if not, with three, if not, then with two or even one, and that is sufficient to please the Supreme Personality of Godhead .
(the above is the beginning- from karma yoga  thru to bhakti yoga -dovetailing what we have for the service of the Supreme)
2.) Aug 24 1968 Montreal
Devotee: Well, karma-yoga...
Prabhupāda: Karma-yoga means just to dovetail your karma with yoga principles to arrive to the bhakti-yoga.
Devotee: To eventually arrive.
Prabhupāda: Yes. That is karma. That is not bhakti-yoga. But the aim is to arrive at the bhakti-yoga. Is it clear? That's all. Just try to understand in this way. It is very good.
Devotee (2): Is it the same thing with haṭha-yoga?
Prabhupāda: No, haṭha-yoga is not bhakti-yoga.
3.) Dec 20 1968 LA
It is not inertia. "I have got... Chanting Hare Kṛṣṇa, I shall go and sit down, eat at the expense of others and chant Hare Kṛṣṇa." No. This is karma-yoga. Prāṇair arthair dhiyā vācāḥ. You have to employ your life, your money, your words, and your intelligence, all for Kṛṣṇa. That is Kṛṣṇa consciousness. If you have got enough money, spend it for Kṛṣṇa. Don't stock it. The more you spend, more you become balanceless for spending Kṛṣṇa, then more you are benefited. This is the process.
That will be taught in the karma-yoga section. And how one can, unless one is spiritually advanced how he can sacrifice his hard-earned money for Kṛṣṇa? Everyone thinks, "Oh, I have earned this money working so hard. Why shall I spend it for Kṛṣṇa? Let me keep it. I shall do it for my sense gratification." This is, this kind of advancement is no value. You see. How one has learned to sacrifice everything for Kṛṣṇa.
Just like Arjuna. He sacrificed his whole family for Kṛṣṇa. In the beginning he hesitated, "How can I kill my family members, this fight?" And when he became Kṛṣṇa conscious, "Never mind, I shall kill all of them."This is called sacrifice. This is Kṛṣṇa conscious. He sacrificed all sentiments, all connection, everything for Kṛṣṇa. That is called sannyāsa, real sannyāsa. Although he was a warrior, a fighter, a householder having more than dozen wives, but he was sannyāsa. Because he sacrificed everything for Kṛṣṇa. That is wanted. That is Kṛṣṇa conscious.
So everyone can test how far he has advanced simply by this, "How far I have become prepared to sacrifice everything for Kṛṣṇa?" He doesn't require to take certificate from others. He can test himself, "How far I am prepared?" 
4.)  Sept 16 1976
Pṛthivīte āche yata nagarādi. That is His (Lord Caitanya's) mission. It is not that "Become a big Vaiṣṇava and sit down and imitate." This is all rascaldom. So don't follow this thing. So at least we cannot advise you in that way. We have learned from our Guru Mahārāja that preaching is very, very important thing, and when one is actually an experienced preacher, then he is able to chant Hare Kṛṣṇa mantra without any offense. Before that, this so-called chanting of Hare Kṛṣṇa mantra, you may practice without any offenses...And giving up all other business to make a show of a big Vaiṣṇava, that is not required. Thank you very much. (end)
5.) Feb 11 1976 Mayapur--
Real life is to become mahā-bhāgavata.You cannot become a mahā-bhāgavata all of a sudden,but from kaniṣṭha-adhikārī,arcāyām eva haraye yaḥ pūjāṁ śraddhayehate na tad-bhakteṣu cānyeṣu
sa bhaktaḥ prākṛtaḥ smṛtaḥ
Prākṛtaḥ stage, so prakṛtaḥ stage means just like we are worshiping The Deity, but not only we shall worship Deity but we make advancement. What is that advancement? To become gradually a preacher. That is madhyama-adhikārī, second stage, preacher. Preacher means that,
īśvare tad-adhīneṣu
bāliśeṣu dviṣatsu ca
prema-maitrī-kṛpā upekṣāḥ
yaḥ karoti sa madhyamaḥ
When you become fully Kṛṣṇa conscious by worshiping the Deity regularly, as we have got prescription to rise early in the morning, offer maṅgala-ārati, then kīrtana, then class, in this way practicing, practicing. When you become advanced Kṛṣṇa conscious, then your natural tendency will be how to preach. So long you do not develop this tendency for preaching, simply remain in kaniṣṭha-adhikārī, you do not know how to deliver others, na tad-bhakteṣu cānyeṣu, you do not know how to receive elevated, one elevated devotee, you do not know how to do good to others. So Caitanya Mahāprabhu's mission is not to keep one in the kaniṣṭha-adhikārī, especially those who are born in India. He says
bhārata-bhūmite manuṣya-janma haila yāra
janma sārthaka kari' kara para-upakāra
[Cc. Ādi 9.41]
This is principle, para-upakāra, because everyone is suffering. So in the lower stage, everyone should take part very diligently in the worship of the Deity, śrī-vigrahārādhana-nitya-nānā-sṛṅgāra-tan-mandira-mārj anādau **. One should be engaged, everyone should be engaged, śrī-vigrahārādhanam, with Deity worship.What is that Deity worship? Sri, śrī-vigrahārādhana-nitya-nānā-śṛṅgāra **. To decorate the Deity very, very nicely, śṛṅgāra. Tan-mandira-mārjanādau, and to keep the temple, all through, very clean. This kaniṣṭha-adhikārī should be fully engaged in these things, then he becomes gradually, I mean to say, elevated in the madhyama-adhikārī.
In the madhyama-adhikārī he can see four things. What is that? Four things means, first of all the Supreme Lord, īśvara, the controller, he can see. He can see means he understands, he appreciates, he can conceive,"Yes, the Supreme Lord is there". There is no more theoretical. So īśvara, and tad-adhīneṣu, and persons who have become devotee, he can understand, "Here is a devotee." Īśvare tad-adhīneṣu bāliśeṣu. Bāliśa means he knows imperson. They do not know what is God, what is to be done, they are called bāliśa. Just like children, arbhakaḥ, bāliśa. And then dviṣāt, envious. Just like you have experienced so many rascals, as soon as they hear of God, immediately they become agitated. They are called dviṣāt, envious, demons. So four things, God, His devotees, and the innocent person, and the demonic atheist. He can see, madhyama-adhikārī. And then he behaves with these four classes of men differently. What is that? Prema, for Kṛṣṇa, the Supreme Lord, how to increase love. That is first business, prema. And those who are devotees, to make friendship with them maitrī. Those who are higher than him, he should offer very respectful obeisances, those who are equal, treat them with nicely, and those who are lower then instruct them, bāliśeṣu. Those who are innocent, how to raise him in Kṛṣṇa consciousness. This is preaching. And dviṣatsu, upekṣaḥ, those who are atheist, don't associate with them. Don't associate with them. That is the madhyama-adhikārī.
And uttama-adhikārī, that is very rarely attained, this stage. Uttama-adhikārī, has only equal, one vision, samaḥ sarveṣu bhūteṣu mad-bhaktiṁ labhate. The uttama-adhikārī, he does not think that "He is envious," or "he is this," or "he is that," he sees that everyone is engaged in Kṛṣṇa consciousness. That is not to be imitated. That Prahlāda Mahārāja is like that. He did not know who is his enemy and who is friend. No, he did not know. He is uttama-adhikārī, mahā-bhāgavata. 
6.) SB 4.14.41 purport-.Brāhmaṇas, the topmost section of human society, are mostly devotees. They are generally unaware of the happenings within the material world because they are always busy in their activities for spiritual advancement. Nonetheless, when there is a calamity in human society, they cannot remain impartial. If they do not do something to relieve the distressed condition of human society, it is said that due to such neglect their spiritual knowledge diminishes.
Some conclusions---
In the above statements Srila Prabhupada has made it very clear-if one wants to leave the material platform (kanistha-the sensual, mental, and intellectual platform) and come to the spiritual platform, he must seriously do Deity worship and preach about Krsna. Otherwise , eventually,his or her spiritual potency and knowledge  will diminish. The Krsna Consciousness Movement is a preaching movement as taught to us by Caitanya Mahaprabhu.If one wants to simply do deity puja, which is good, he will become locked up on that materialistic kanistha adhikari platform and think this is all I have to do. and not advance to the actual spiritual platform of Madhyama adhikari.
Hare Krsna
Compiled by damaghosa das.

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