The Bhagavad-gita says that out of many thousands of human beings, one may try to make perfection of his life. Man is an animal, but he has one special prerogative, rational thought. What is that rational thought?
Reasoning power, argument.
Now, reasoning power is there in dogs and cats as well. Suppose a dog comes up to you; if you say, “Hut!” he’ll understand. The dog will understand that you don’t want him. So, he has some reasoning power. But what is the special reasoning power of the human being?
As far as the bodily necessities are concerned, the reasoning power is there even in the animal. If a cat wants to steal some milk from your kitchen, she has very nice reasoning power: she is always looking to see when the master is out and she can take. So, for the four propensities of animal life—eating, sleeping, mating and defending—there is reasoning power even in beasts. Then, what is the special reasoning power of the human being, by which he is called the rational animal?
The special reasoning power is to inquire, “Why am I suffering?” This is special reasoning. The animals are suffering, but they do not know how to remedy the suffering. But human beings are making scientific advancement and philosophical advancement, cultural advancement, religious advancement—progress in so many lines—because they want to be happy. “Where is the point of happiness?” This reasoning power is especially given to the human being. Therefore, in the Gita, Krishna says, “Out of so many men, one may know Me.”
When there is some impetus to awaken this reasoning power, it is called brahma jijnasa. This is found in the Vedanta-sutra. The first verse says that now, this human form of life is meant for asking the question of how to solve the problem of suffering.
I am undergoing troubles by nature’s laws, and by the state’s laws. So the question of freedom is how to become free from all these troubles. The Vedanta-sutra also says that the soul, my actual self, is by nature joyful. Yet, I am suffering. Lord Krishna further says that when these questions arise, gradually one comes to God. Those who have awakened to these questions are said to lie on the path of perfection. And, when the question of God and our relationship with God comes, that is our final perfection of life which can be attained by the simple method of chanting as propagated by Lord Chaitanya Mahaprabhu who was none other than Krishna Himself.
In this age this is the easiest method of self-realization. Simply chant Hare Krishna. It can be done by everyone. In any country, in any place, this can be performed. Therefore it is the easiest. You can chant very easily: Hare Krishna Hare Krishna Krishna Krishna Hare Hare/Hare Rama Hare Rama Rama Rama Hare Hare.
Ref: Krishna Consciousness The Topmost Yoga System authored by Srila Prabhupada (Founder – Acharya, ISKCON)