There is a misconception that Dhamma can be achieved by depending exclusively on our will and know-how. The idea that the Dhamma is a passive entity, waiting to be discovered by anyone who finds the means to achieve it.
The Dhamma is like the ocean. It has an unstoppable force. While some are caught in its current and dragged to the other shore, others are rejected as corpses in a state of decomposition, does not want them.
As it is so extremely easy for some and completely impossible for others, it would seem that we are facing a true predestination. And in a certain way, it is. It depends on ourselves our destiny. The kamma is our product and it is our condemnation. And the kamma is unbreakable despite our efforts, good intention or encouragement.
But not only of us. There are conditions that do not happen because of us, but are external, and that can prevent the achievement of total awakening.
General conditions to reach arahantado are, among others, to have been born in a historical moment in which there was a Sammasambuddha, in a favorable environment to get in the way of it. Having been educated or trained to develop the higher cerebral faculties …
Outside of the time of Sammasambuddha, in an exclusive manner, the path of the Paccekabuddha, or solitary buddha, who can not temporally coincide with the existence in the world of a Sammasambuddha, is open.
These conditions, prior to birth or direct cause thereof, are unmanageable within the present life. It is necessary to come with those conditions.
Then there are those that depend on our activity in this life. To attain sufficient personal and mental development, to be willing to learn, to attain mastery in practice, to contact the Sammasambuddha, to use the necessary effort are necessary conditions for enlightenment, but not sufficient.
All that takes you to the shore.
Now comes the final test.
You throw yourself into the current and at that point two things can happen, or else, it drags you and already, leaving you to carry without resistance, in this or in the following lives you inevitably reach the other shore, or, the Dhamma rejects you as a dead body, corrupt and bloated.
There is nothing to do there.
The Dhamma returns you.
A Sammasambuddha can help you in your phases of practice, so you need to trust him. If you manage to enter the stream, you succeeded. Sooner or later, in this or in the following lives you will reach in final Nibbāna. If you do not succeed, there is no way. Ask yourself why the Dhamma does not love you.
There’s nothing to do.
There are few who come to this shore.
Of them, very few who throw themselves.
Of them are the majority that the Dhamma rejects.
The least, are the blessed who manage to cross. Only the blessed ones.
AN 4. Collection of speeches grouped numerically 
The book of eight 
AN 8. 19. Pahārāda Sutta
«In addition, just as the Great Ocean is stable and does not exceed its coasts, in the same way my disciples – even for the sake of their lives – do not go beyond the rules of the practice that I have formulated for them. The fact that my disciples -even for the sake of their lives- do not go beyond the rules of the practice that I have formulated for them, is the second amazing and incredible thing related to this Dhamma and Discipline that the monks contemplate continuously, delighting in he.
«Furthermore, just as the Great Ocean does not tolerate the presence of dead bodies, being that any dead body found in the great Ocean is washed and carried to shore, to dry land, in the same way if an individual he is unscrupulous, evil, impure and suspicious in his intentions, that hides his acts, is a pseudo-ascetic who claims to be an ascetic, a pseudo-noble who claims to be noble, rotten inside, swollen with desires, grimy by nature, the Sangha he has no communion with him. Even if he were sitting in the middle of the Sangha, he would still be far from the Sangha, as the Sangha would be away from him. The fact that the Sangha has no communion with an unscrupulous, evil, impure and suspicious individual in his intentions, who hides his acts, a pseudo-ascetic who claims to be an ascetic, a pseudo-noble who claims to be noble, rotten inside, swollen with desires, filthy by nature and that, although he is sitting in the middle of the Sangha, he is also far from the Sangha, as the Sangha is far from him, it is the third amazing and incredible thing related to this Dhamma and Discipline that the monks contemplate continuously, reveling in him.
«Also, monks, just like the Great Ocean is being inhabited by powerful and great creatures like whales, whales that eat whales, whales that eat whales that, in turn, eat other whales, asuras , the nagas and the gandhabbas, whose bodies are in the depth of one hundred yojanas … two hundred yojanas … three hundred yojanas … four hundred yojanas … five hundred yojanas; in the same way this Dhamma and Discipline is being inhabited by powerful and great beings, such as those who enter the stream and those who realize the fruit of entering the stream, those who return once and those who realize the fruit of a only return, those that do not return and those that realize the fruit of the non-return, the arahants and those that realize the fruit of the arahantado. The fact that this Dhamma and Discipline is being inhabited by powerful and great beings – like those who enter the stream and those who realize the fruit of entering the stream, those who return once and those who realize the fruit of a only return, those who do not return and those who realize the fruit of non-return, arahants and those who perform the fruit of the arahantado, is the amazing and amazing eighth thing related to this Dhamma and Discipline that the monks contemplate continuously, reveling at.