We can talk about gradual cultivation and sudden enlightenment in terms of practice and experience, but we can also use these categories to understand the different ways in which the Dharma is presented. Way back in Tibetan history, for instance, there was a big debate about whether to adopt toe Chinese way of presenting the Dharma which emphasised suddenness or the Indian Mahayana approach that presented a gradualist path. They opted for the Indian presentation, but in reality Tibetan Buddhism remains a mix of the two.
In the standard Tibetan gradualist approach, especially Lam Rim, Buddhism is presented as a series of "Paths" as follows:
1. Path of Accumulation: This means listening to teachings. Worshipping and being in the presence of the guru is regarded as extremely important: "The path begins with strong reliance / on my kind teacher, source of all good."
2. Path of Preparation: This means going away to reflect upon and apply the teachings one has received, testing them and finding them to be authentic in experience as well as in concept.
3. Path of Seeing: This is the tipping point when the realisation of the truth of the Dharma penetrates sufficiently to drive out negative emotion. This is equivalent to entering the path in an irreversible way since such experience cannot be erased and it naturally lessens one's greed, hate and delusion.
4. Path of Meditation: Here this is the process of fully integrating the experience of realisation.
5. Path of No-More-Learning: This is the state called asekha in Pali. One has learnt the essential truth. One is awakened. One now lives within the Dharma.
Now it can be readily seen that although this is presented as a stepwise progression, it still contains a critical tipping point which is really equivalent to sudden awakening (Zen) or the awakening of faith (Pureland).
So we can see that gradual and sudden methods of presentation are actually just different ways of wrapping up the same message.
In Pureland and Zen it is also very important to listen to the teachings and spend time with the teacher. It is recognised that progress does occasionally hppen in other ways, but being with the teacher is the royal road in all these schools of Buddhism because it is difficult to see one's own case and without a living example one is likely to just go round in circles massaging one's favourite delusion about the spiritual life.
In Zen and Pureland it is also very important to test the teaching in one's own case and here there is a particular emphasis upon inward examination (naikan, nei quan) leading to contrition and softening of the heart.
The path of 'Seeing', of course, equates with satori/kensho in Zen and with shinjin in Pureland. It is a universal Buddhist point that there are thresholds that once passed cannot be undone. Even is an awakened person goes completely off the rails they cannot reach that state of not knowing what they know and sooner or later this is going to pull them back on course, perhaps with much renewed contrition, but certainly with greater wisdom and compassion. In fact, sometimes it takes a 'fall' to brush off the old habits that still cling.
What is called the Path of Meditation does not particularly mean having a practice of silent sitting. It means the process of profiting from the insight one has had. This is going to involve contemplation of one sort or another but this will arise naturally whether one has a formal practice or not.This is not a matter of applying a technique. It is the fact that once one's initial foundation of faith/insight is established, daily life is going to present a whole series of small and greater encounters in which the implications become apparent. When this takes place within a spiritual community it can go rapidly and inspire everybody around. When it is happening in the midst of ordinary worldly circumstance the practitioner is likely to encounter resistance. Friends and relatives do not like one to change - "I don't know what's happened to him - he used to be such a lad, but now he's no fun any more." Actually he is having a different kind of fun.
The Path of No-More-Learning is what, in Pureland, we call anjin, "settled faith" or "heart at peace". It is not a passive state. It is full vibrancy of life.
So, now, you see, I have managed to describe the sudden paths of Zen and Pureland in gradualist terms just as we were able to see the Tibetan gradual path as being a description of sudden awakening. It is all a matter of perspective. When you look at a tin can end on it is a circle. When you look at it from the side it is a rectangle. One could argue all day about whether tins are round or square but it is better to open the tin and eat the contents. Ah! delicious!