In the Bhagavad-gita, last portion of eighteenth chapter, it is said that nobody is dearer to Krsna than anybody on the earth except the person who is engaged in preaching the most confidential philosophy of life, namely surrendering unto Krsna, leaving aside everything material or spiritual.
Letter to Kirtanananda Maharaja, 18 February, 1970
Regarding your headaches, your bowels are not clear. This is the cause of the problem. So you should take more milk and fruits, and eat less wheat and rice. If sandalwood oil is available, you try to massage on your shaved head. Let me know how this trouble is improving. A brahmacari should not have any complaint of bodily disease.
Letter to Tosana Krishna, 17 February, 1969
As far as your attachment for tending the Deities is concerned by no means this can be considered material attachment, but this is our real desireless state to be always engaged twenty four hours in the service of the Lord. But if the facility for serving the Deities is not there, then we should not be discouraged. This is real detachment. When Caitanya Mahaprabhu was touring all over India He did not bring the Deities with Him. So in our travelling and preaching, Deity worship is not essential but if it is done nicely it can be a very attractive aspect of our preaching work.
Letter to Sudama, 16 February, 1973
Regarding Rudra dasa, he can worship Gaura-Nitai in his home. The most important element for their worship is the chanting of the Hare Krishna Mantra. They can have at least one arati and whatever foodstuffs are prepared can be offered.
Letter to Govardhana dasa, 15 February, 1975
Regarding your insurance policy, I do not wish to engage you in litigation; that is not a sannyasi's business. In India, since I left, people have grabbed my money up to many thousands of rupees. That Hitsaran took away 2000 Rs, the landlord has taken away more than 2000 Rs, but what can I do? If I go to litigation I will have to put myself in so many anxieties. It is better to forget. If peacefully you can draw the money from your father that is all right. I do not know what kinds of devious means you want to use in this connection, but any means, if it does not put you into difficulties, will be acceptable.
Letter to Kirtanananda, 14 February, 1969
A devotee does not want even salvation. Why Lord Caitanya says "birth after birth"? The Salvationists, they want to stop, the voidists, they want to stop this material way of life. But Caitanya Mahaprabhu says, "birth after birth." That means he is prepared to undergo all kinds of material pangs birth after birth. But what He wants? He simply wants to be engaged in the service of the Lord. That is the perfection.
Lecture on Bhagavad-gita 6.1, Los Angeles, 13 February, 1969
Regarding your idea of having an installation ceremony for the Deities, it is very good suggestion, and you may also have the sacrificial fire. The Deities should be bathed with milk, and while bathing, They must have covering of thin cotton cloth, and the whole Body and the clothing should be wet by pouring the milk. You can see the picture of this in the new Back To Godhead, and perhaps you saw the ceremony when it was held in New York. The Deities should be decorated with sufficient flowers and nice gorgeous dresses and ornaments. Beforehand, you should polish the Bodies with a mixture of tamarind pulp and fullers earth. Apply the pulp on the Bodies, then rub it and then polish nicely with tissue paper. This will gave a very good shine. Then bath the Deities with milk, and dress very nicely with ornaments, and place Them on the throne with flowers, candles, etc.
Letter to Satsvarupa, 12 February, 1969
As far as the College and University Lecture Party is concerned that is very important and it may be done very seriously. As a matter of fact Tamala Krishna Maharaja is here and he suggests that our educated gentlemen travel with his buses. So what is the use of working alone? Working conjointly is better.
Letter to Svarupa Damodara, 11 February, 1976
The spirit soul is impossible to find out by materialistic scientific means, but if one will hear from the right authority, he may understand. The gentleman is disappointed that probably no one will ever know about spirit, but this is not true. We know what is spirit, how does it work, how does it transmigrate from one body to another or from one planet to another. We know these very scientifically, and we are firmly convinced about it. We can refute any dogmatic arguments against this conviction, and how do we do that? Simply because we start our understanding from the data of authoritative sources like Krishna or His representative.
Letter to Govinda Dasi, 10 February, 1969
Yamaraja is explaining that "He is above me, the supreme controller, and He is the..., He is such controller that He creates, He maintains, and He annihilates also." We become so much harassed even for creating a family and maintaining them. We have become so much harassed. And foolishly we claim that we are the Supreme Personality of Godhead who creates the whole cosmic manifestation. And Brahma, Visnu, Mahesvara, the directors of creation department, maintenance department, and annihilation department... Annihilation also required. That annihilation is one of the business of Krsna, or God, for this material world. Not in the spiritual world. There is no annihilation. Here it is required. Sometimes, because everyone has come here to lord it over the material nature, so there must be an ultimate situation when it becomes intolerable, and therefore Krsna has to annihilate, finish. That is kalki-avatara.
Lecture on Srimad-Bhagavatam 6.3.12-15, Gorakhpur, February 9, 1971