"It is my great delight that you have realized how Krishna Consciousness has transformed lives from drug addicted hippies to loving servants of Krishna and humanity. Loving service of Krishna is so exalted, that it automatically turns loving service to humanity. Krishna is just like the root of the tree and if you pour water on the root, it automatically reaches other parts of the tree.
It is said in the Srimad-Bhagavatam,
yasyasti bhaktir bhagavaty akincana
sarvair gunais tatra samasate surah
harav abhaktasya kuto mahad-guna
manorathenasati dhavato bahih
If a person has unflinching devotion at the lotus feet of Hari (God), then all the good qualities of great personalities like the demigods, automatically becomes manifest in the person of a devotee. Whereas a non-devotee, even he is decorated with material qualities, he is forced to act on the material plane and he stays in temporary field of activities.
The idea is that spirit-soul is eternal and the material body is temporary, or for the sake of sense gratification. The mental plane is also material. People being forced to stay on the material platform, they are planning for temporary happiness, and being frustrated, they are jumping from one platform to another which are all temporary.
But, fortunately, if one becomes situated on the platform of Krishna Consciousness, then his jumping over material platforms becomes ceased. It is confirmed in the Bhagavad-gita as follows: yam labdhva caparam labham, manyate nadhikam tatah - upon gaining this, he thinks that there is no greater gain.
So, at the present moment, there is great necessity to give to the human society Krishna, or God. Everyone speaks of God, but nobody has clear idea what is God, or where is God. We Hare Krishna people are trying to do our best to say, 'here is God, Krishna.'
So, please try to co-operate with this movement and I am sure the world will be happy."
(Srila Prabhupada letter, June 11, 1975)