Gavampati states to a group of elder bhikkhus that he has heard face-to-face with the Buddha that he who sees any one of the Four Truths also sees all of them.
Read the Sutta
Index of Available translations: SN 5.56.30
This is understood in the commentaries to mean 'in the same instant', but we shall show that the meaning is 'upon arriving at the point of seeing, as it really is, in it's totality'.
This is a very interesting sutta from the point of view of doubtful matters.
Bhk. Bodhi, in a note to the print edition, confirms my belief that this statement is not made elsewhere in the four nikaya, by the Buddha or anyone else.
What is said elsewhere is that each of the four truths is the equivalent of each of the others.
It is quoted it the Vissudhi Magga and in Points of Controversy.
Curiously in Points of Controversy Gavampati's point is defended by the Thereavadans in spite of it's being (at least on the face of it ... we will get to that) in contradiction to numerous places where awakening is stated to be a gradual process.
That awakening is an instantaneous (that is, all or nothing) event is the position of at least some Zen Buddhist schools.
How can we reconcile this dilemma without dismissing the statement of Gavampati as being false?
The key term here that must be understood is 'passati', 'seeing'.
The terms used for the Stream-enterer are:
ñāṇa and dassana, 'knowing and seeing'. The difference between dassana and passati is that the former is an intellectual understanding whereas the latter is a penetrating vision, discovery, realization, of the actual reality.
So we can say there is, up to the point of passati, a gradual expansion of comprehension, 'dassana,' which, at a certain point results in a penetrating, comprehensive, all-encompassing vision of all aspects of a single truth which can be expressed in each of four ways (an awakening which could be called 'instantaneous').
Said another way, you cannot see the full scope of the idea that everything is pain until you see that it is a result of thirst. One cannot see the full scope of the statement that existence itself is pain, for example, until one is able to see that it is thirst-motivated behavior which brings about existence to that point one is continuously trying to awaken the existing being, that is to 'awaken myself,' which is to say: 'to awaken myself within myself,' which cannot be done because awakening is outside of existence, and that by ending thirst that pain will end and that the way to end thirst is to mold one's behavior such that it does not exhibit any form of self-interest, i.e., thirst, that is, follow the Magga.
And it is the same whether you approach the problem from this or any of the other three Truths.
There is a gradual course which leads up to a sudden, comprehensive, liberating vision, and one does not fully 'see' until one has reached that point.