So risk of impersonal realization is that because in the impersonal feature you cannot enjoy that blissfulness eternally, therefore sometimes — not sometimes, mostly — they come back again into the material world. Because by nature we are jubilant, in the impersonal feature of brahmajyoti, we cannot enjoy life. Therefore again we come back to this material enjoyment. Just like by an airplane, you want to go higher and higher, but if you don't get the shelter, a shelter in another planet, you will have to come back again to this planet.

Aruhya krcchrena param padam tatah patanty adhah anadrta-yusmad-anghrayah: [Srimad-Bhagavatam 10.2.32] "Unless you become elevated to the position of serving the Supreme Personality of Godhead face to face, simply by impersonal Brahman realization you cannot become happy. Therefore for enjoyment…" Enjoyment means variety, the varieties of enjoyment. "You come down again to the material world." We have seen it practically. Many big, big sannyasis and transcendentalists, they give up this world as mithya or false and take to sannyasa [renounced, monk life], but after some time, again they come back to this material world for executing philanthropic activities like opening hospitals or opening schools and other philanthropic activities. It so happens because they cannot fully realize the Absolute Truth as the Supreme Person, they again come to these material persons.

Therefore in the Bhagavad-gita you will find, Krishna says, bahunam janmanam ante jnanavan mam prapadyate, which means, "After many, many births, the jnanis, after speculative knowledge, when actually they come to the platform of knowledge, they surrender unto Me or they understand the Supreme Personality of Godhead."

The next line is, vasudevah sarvam iti sa mahatma sudurlabhah. One who can understand Krishna, whose another name is Vasudeva, so He is everything, He is the origin of everything, one who can understand, He is supposed to be mahatma, the liberated soul, or the great soul. Mahatma. Maha means great. Atma means soul. But sa mahatma sudurlabhah. It is very difficult to find out such mahatma. So the Krishna devotees who are engaged in these missionary activities, Krishna consciousness movement, they are not ordinary persons. They are mahatma, but very rarely to be found. Sa mahatma sudurlabhah.

So although everyone is searching after Krishna, either in impersonal Brahman or localized Paramatma, the person who has understood Krishna, the Supreme Person, he is the greatest, I mean to say, successful man within this world.

Srila Prabhupada Excerpt from a lecture given in Geneva, Zurich on June 1st 1974.