Simply put, people’s capabilities vary. Why do some people understand things quickly and others slowly or not at all? It basically comes down to accumulated merit/perfections and rightly directed effort.
Buddhahood and arahantship are literally the highest possible achievements a being can aspire to. Stream-entry is better than rulership over the entire world (Dhp 178), and it would be worth it to be stabbed by 300 spears a day for a hundred years straight to attain it (SN 56.35)—even still they need up to 7 whole lifetimes to develop before attaining arahantship. These are truly noble goals, worthy of respect. So it’s no wonder that many people do not attain in a single life. And let’s be honest: a lot of people want the benefits of enlightenment without having to give up their attachments.
When he had spoken, Moggallāna the Accountant said to the Buddha, “When his disciples are instructed and advised like this by the worthy Gotama, do all of them achieve the ultimate goal, extinguishment, or do some of them fail?”
“Some succeed, while others fail.”
“What is the cause, worthy Gotama, what is the reason why, though extinguishment is present, the path leading to extinguishment is present, and the worthy Gotama is present to encourage them, still some succeed while others fail?”
“Well then, brahmin, I’ll ask you about this in return, and you can answer as you like. What do you think, brahmin? Are you skilled in the road to Rājagaha?”
“Yes, I am.”
“What do you think, brahmin? Suppose a person was to come along who wanted to go to Rājagaha. He’d approach you and say: ‘Sir, I wish to go to Rājagaha. Please point out the road to Rājagaha.’ You’d say to them: ‘Here, worthy man, this road goes to Rājagaha. Go along it for an hour, and you’ll see a certain village. Go along an hour further, and you’ll see a certain town. Go along an hour further and you’ll see Rājagaha with its delightful parks, woods, meadows, and lotus ponds.’ Instructed like this by you, they might still take the wrong road, heading west. But a second person might come with the same question and receive the same instructions. Instructed by you, they might safely arrive at Rājagaha. What is the cause, brahmin, what is the reason why, though Rājagaha is present, the path leading to Rājagaha is present, and you are there to encourage them, one person takes the wrong path and heads west, while another arrives safely at Rājagaha?”
“What can I do about that, worthy Gotama? I am the one who shows the way.”
“In the same way, though extinguishment is present, the path leading to extinguishment is present, and I am present to encourage them, still some of my disciples, instructed and advised like this, achieve the ultimate goal, extinguishment, while some of them fail. What can I do about that, brahmin? The Realized One is the one who shows the way.”
-MN 107
“Mendicants, a farmer has three urgent duties. What three? A farmer swiftly makes sure the field is well ploughed and tilled. Next they swiftly plant seeds in season. When the time is right, they swiftly irrigate or drain the field. These are the three urgent duties of a farmer. That farmer has no special power or ability to say: ‘Let the crops germinate today! Let them flower tomorrow! Let them ripen the day after!’ But there comes a time when that farmer’s crops germinate, flower, and ripen as the seasons change.
In the same way, a mendicant has three urgent duties. What three? Undertaking the training in the higher ethics, the higher mind, and the higher wisdom. These are the three urgent duties of a mendicant. That mendicant has no special power or ability to say: ‘Let my mind be freed from defilements by not grasping today! Or tomorrow! Or the day after!’ But there comes a time—as that mendicant trains in the higher ethics, the higher mind, and the higher wisdom—that their mind is freed from defilements by not grasping.
So you should train like this: ‘We will have keen enthusiasm for undertaking the training in the higher ethics, the higher mind, and the higher wisdom.’ That’s how you should train.”
-AN 3.92
“Mendicants, when a mendicant is not committed to development, they might wish: ‘If only my mind were freed from the defilements by not grasping!’ Even so, their mind is not freed from defilements by not grasping. Why is that? You should say: ‘It’s because they’re undeveloped.’ Undeveloped in what? The four kinds of mindfulness meditation, the four right efforts, the four bases of psychic power, the five faculties, the five powers, the seven awakening factors, and the noble eightfold path.
Suppose there was a chicken with eight or ten or twelve eggs. But she had not properly sat on them to keep them warm and incubated. Even if that chicken might wish: ‘If only my chicks could break out of the eggshell with their claws and beak and hatch safely!’ Still they can’t break out and hatch safely. Why is that? Because she has not properly sat on them to keep them warm and incubated.
In the same way, when a mendicant is not committed to development, they might wish: ‘If only my mind were freed from the defilements by not grasping!’ Even so, their mind is not freed from defilements by not grasping. Why is that? You should say: ‘It’s because they’re undeveloped.’ Undeveloped in what? The four kinds of mindfulness meditation, the four right efforts, the four bases of psychic power, the five faculties, the five powers, the seven awakening factors, and the noble eightfold path.
When a mendicant is committed to development, they might not wish: ‘If only my mind were freed from the defilements by not grasping!’ Even so, their mind is freed from defilements by not grasping. Why is that? You should say: ‘It’s because they are developed.’ Developed in what? The four kinds of mindfulness meditation, the four right efforts, the four bases of psychic power, the five faculties, the five powers, the seven awakening factors, and the noble eightfold path.
Suppose there was a chicken with eight or ten or twelve eggs. And she properly sat on them to keep them warm and incubated. Even if that chicken doesn’t wish: ‘If only my chicks could break out of the eggshell with their claws and beak and hatch safely!’ Still they can break out and hatch safely. Why is that? Because she properly sat on them to keep them warm and incubated.
In the same way, when a mendicant is committed to development, they might not wish: ‘If only my mind were freed from the defilements by not grasping!’ Even so, their mind is freed from defilements by not grasping. Why is that? You should say: ‘It’s because they are developed.’ Developed in what? The four kinds of mindfulness meditation, the four right efforts, the four bases of psychic power, the five faculties, the five powers, the seven awakening factors, and the noble eightfold path.
Suppose a mason or their apprentice sees the marks of his fingers and thumb on the handle of his adze. They don’t know how much of the handle was worn away today, how much yesterday, and how much previously. They just know what has been worn away. In the same way, when a mendicant is committed to development, they don’t know how much of the defilements were worn away today, how much yesterday, and how much previously. They just know what has been worn away.
Suppose there was a sea-faring ship bound together with ropes. For six months they deteriorated in the water. Then in the cold season it was hauled up on dry land, where the ropes were weathered by wind and sun. When the monsoon clouds soaked it with rain, the ropes would readily collapse and rot away. In the same way, when a mendicant is committed to development their fetters readily collapse and rot away.”
-AN 7.71
In the twenty-five years
since I went forth,
I have not found peace of mind,
even as long as a finger-snap.
Since I couldn’t get my mind unified,
I was racked by desire for pleasures of the senses.
Wailing, with outstretched arms,
I left my dwelling.
Or shall I commit suicide?
What’s the point of living?
For how on earth can one such as me die
after resigning the training?
Then I picked up a razor,
I sat on a cot:
the razor was ready
to slice my vein.
Then the realization
came upon me—
the danger became clear,
and I was firmly disillusioned.
Then my mind was freed—
behold the clear rightness of the teaching!
I’ve attained the three knowledges,
and fulfilled the Buddha’s instructions.
-Thag 6.6
In the twenty-five years
since I went forth,
I have not found peace of mind,
even as long as a finger-snap.
Failing to find peace of heart,
festering with sensual desire,
I cried with flailing arms
as I entered a dwelling.
I approached a nun
in whom I had faith.
She taught me the Dhamma:
the aggregates, sense fields, and elements.
When I heard her teaching,
I retired to a discreet place.
I know my past lives;
my clairvoyance is purified;
I encompass the minds of others;
my clairaudience is purified;
I’ve realized the psychic powers,
and attained the ending of defilements.
I have realized the six kinds of direct knowledge,
and fulfilled the Buddha’s instructions.
-Thig 5.1
