Please accept my blessings. I am in due receipt of your letter of 20, January, 1969, and I have noted the contents. You have written that you are unable to find a girl who is available for marriage, and so for the present, you have no choice but to hold off on your marriage plans. Anyway, I always recommend that one should try to remain brahmacari if possible, and if you think that this will be possible for you, you should try for it.
In your letter you have asked many questions, and I will try to answer them for you herewith. Firstly, the Gayatri Mantra is not to be said loudly. Gayat means to sing, but singing can be done loudly or very softly. The Gayatri Mantra should be sung in a low whispering voice. Regarding the Brahman Pucha stages, this matter is described in the 13rd chapter of Bhagavad-gita As It Is. So far as the 10 sense organs, they are eyes, ears, nose, mouth, touch, these are the five sense organs for acquiring knowledge. The five moving organs are the legs, hands, tongue, genital, and rectum. Five objects of the senses are beauty, taste, smell, sound, and touch. The five gross elements are earth, water, fire, air, and ether. The four subtle elements are mind, ego, intelligence, and consciousness. Above these is the soul, and above the soul is the Supersoul.
In tending the deities, you may wash Balarama first, before washing Krishna. Krishna is always non-different from the deity of Krishna. Regarding your request for the Brihat-Sama mantra, this may be given, but a much better proposal is that you concentrate upon improving the quality of your chanting of Hare Krishna Mantra. This is more important consideration for the present time.