The Buddha mentions impermanence. Whether something that is impermanent of lasts only an ‘instant’ is relative. 100 year lifespan of a person is an instant when compared to the lifespan of the universe. He mentions that matter lasts longer and that the mind is changing all the time, relatively:
But when it comes to that which is called ‘mind’ or ‘sentience’ or ‘consciousness’, an uneducated ordinary person is unable to become disillusioned, dispassionate, or freed. 2.2Why is that? 2.3Because for a long time they’ve been attached to it, thought of it as their own, and mistaken it: 2.4‘This is mine, I am this, this is my self.’ 2.5That’s why, when it comes to this mind, an uneducated ordinary person is unable to become disillusioned, dispassionate, and freed.
But an uneducated ordinary person would be better off taking this body made up of the four primary elements to be their self, rather than the mind. 3.2Why is that? 3.3This body made up of the four primary elements is seen to last for a year, or for two, three, four, five, ten, twenty, thirty, forty, fifty, or a hundred years, or even longer.
But that which is called ‘mind’ or ‘sentience’ or ‘consciousness’ arises as one thing and ceases as another all day and all night. 4.2It’s like a monkey moving through the forest. It grabs hold of one branch, lets it go, and grabs another; then it lets that go and grabs yet another. 4.3In the same way, that which is called ‘mind’ or ‘sentience’ or ‘consciousness’ arises as one thing and ceases as another all day and all night.SuttaCentral
This sutta describes an interesting investigation or analysis (yonisomanasikara) into body and mind, which then leads into a contemplation on causality/DO- which interesting mirrors the insight into delineation of mind and matter (nama-rupa paricceda nana) which leads to insight into causality (paccaya parigghaha nana), of the Purification of views (ditti visuddhi) stage of the Visuddhimagga.
Further ‘evidence’:
Then a certain bhikkhu approached the Blessed One … and said to him: “Venerable sir, it is said, ‘the world, the world.’ In what way, venerable sir, is it said ‘the world’?”
“It is disintegrating, bhikkhu, therefore it is called the world. And what is disintegrating? The eye, bhikkhu, is disintegrating, forms are disintegrating, eye-consciousness is disintegrating, eye-contact is disintegrating, and whatever feeling arises with eye-contact as condition … that too is disintegrating. The ear is disintegrating … The mind is disintegrating … Whatever feeling arises with mind-contact as condition … that too is disintegrating. It is disintegrating, bhikkhu, therefore it is called the world.”SuttaCentral
Can impermanence be separated from that which is instant? The later commentaries give it time lengths (millions of thought moments in a second) which isn’t found in the suttas, as frankly there is no measure of time when in meditation. However impermanence is at the core of the dhamma.
A certain monk visited another monk and said: “Tell me, friend, how does a monk’s vision become fully purified?”
“Friend, when a monk fully comprehends as they really are the arising and passing away of the six spheres of contact,[2] to that extent his vision becomes fully purified.”
But that monk was dissatisfied with the other’s answer, so he went to another monk…
“Friend, when a monk fully comprehends as they really are the arising and passing away of the five groups of clinging,[3] to that extent his vision becomes fully purified.”
But that monk was dissatisfied with the other’s answer, and he went to another monk…
“Friend, when a monk fully comprehends as they really are the arising and passing away of the four great elements,[4] to that extent his vision becomes fully purified.”
But that monk was dissatisfied with the other’s answer, so he went to another monk…
“Friend, when a monk fully comprehends as it really is that whatever is of a nature to arise is bound to pass away,[5] to that extent his vision becomes fully purified.” SN35.204
Impermanence is at the heart of the definitions of dukkha, asankhata and nibbana:
1.1“Mendicants, conditioned phenomena have these three characteristics. 1.2What three? 1.3Arising is evident, vanishing is evident, and change while persisting is evident. 1.4These are the three characteristics of conditioned phenomena.”
1.6Characteristics of the Unconditioned
2.1“Unconditioned phenomena have these three characteristics. 2.2What three? 2.3No arising is evident, no vanishing is evident, and no change while persisting is evident. 2.4These are the three characteristics of unconditioned phenomena.”
I would say that the 17 thought moments while following the EBT process functionally, cannot be verified experientially, while the EBT process can be verified. Also if millions of thought moments happen every second there would be hundreds of thousands of stimuli from the sense bases being processed every second. This would make it too fast for a person to consciously register anything but a blur. Therefore it doesn’t make logical sense. More helpful would be to think of these things as metaphoric expression, if not scholarly elaborations, IMO.
with metta