illustration (attribution, if any possible, is at the end of the article)
Experienced phenomena 'constantly' change. Yet, the change can be fast or extremely slow… so slow it might be hard to notice!
Experienced phenomena 'constantly' change: at times the 'external' conditions supporting the experience change… at other times, it's mostly the experience itself that changes, because 'internal' expectations changed (from taking the phenomenon for granted or getting bored, to becoming impatient).
Experienced phenomena are impermanent. Things can 'improve', or 'worsen'… according to ourselves, others, both, none ! Losses can allow for new opportunities, gains can become prisons (some high-paying, top jobs certainly feel that way).
In Theravāda countries, anicca vata saṅkhāra — "Impermanent, alas, are all compounds!" — is used after a loved one died.
In general, saṅkhāra may refer to all phenomena, really, but often it refers more specifically to the ideas/representations we have of phenomena (both a result of interacting with them, and an influence on how we'll interact with them!). The sense of loss when someone dies encompasses not only what was but also what (was imagined as what) could have been; the sense of loss (or relief?) is also more linked to our perceived relationship to that person than to who this person truly was, how this person perceived oneself, etc.
Prejudices, preferences, partial blindness, expectations, abusive generalisations —in short, ignorance— pollute 'compounds': the untamed mind often sees only what it desires to see!
The 'alas' is an expedient means, an expression of empathy toward a confused experiencer suffering in that instant… yet, impermanence doesn't call for sadness: sadness only arises from the disappointment born when you expect permanence… No expectation of permanence, no clinging, no surprise and no disappointment!
« Since in this very life a tathāgata is not to be regarded as existing in reality, is it proper for you to assert: "as I understand the doctrine taught by the Exalted One, insofar as a bhikkhu has destroyed the intoxicants/passions, he is broken up and perishes when body is broken up, he exists not after death"? »
— Yamaka sutta (SN 22.85)
Impermanence calls for not taking for granted that experiences will continue as they currently exist. It might call for appreciation in the moment, it might call for not getting disheartened, it might call for appreciating some changes… i.e. it calls for discernment, not for fear of the change/unknown!
Impermanence calls for engagement, for "right effort", for giving rise to the wholesome, cultivating the wholesome, abandoning the unwholesome, and ceasing the unwholesome.
« Three kinds of feelings, monks, are impermanent, compounded, dependently arisen, liable to destruction, to evanescence, to fading away, to cessation: pleasant feeling, painful feeling, and neutral feeling. »
— anicca sutta (SN 36.9)
You cannot step twice into the same river. 'New' is no longer new, expectations arise, generalisations are drawn.
A mind gets used to things (pleasant or unpleasant is irrelevant): there's a strong tendency for the untamed mind to conclude that how it perceives phenomena corresponds to how they inherently are, there's a strong tendency for the untamed mind to conclude that subjective experiences are objective.
But then the experienced reality doesn't comply with your expectations, and expectations themselves evolve… in a perpetual attempt (and stressful fight) to force subjectivity to match objectivity, in a perpetual dissatisfaction.
Part of a more constructive approach is to refrain from creating 'certainties', from defining, from projecting ideals; at the very least, "unless it's necessary". It might turn out it rarely is… necessary.
When faced with a choice between perpetually engaging with reality as it is, or perpetually engaging with biased, disappointing fictions, which one will the wise elect?
It might seem scary to deal with reality without certainties… but to deal with reality based on misrepresentations is worse: the latter indeed guarantees that you'll hit the wall! At least, with mindful presence, you stand a chance ;-)
Buddhism has no specific guideline on supporting teachers, it simply asks for you to consider causality: if you want this living tradition to survive, how are you participating, in practical terms, to make this happen? Nice words, exposure or social media ‘+1’ might feel good, but they do not actually help with the basic necessities: koan.mu/donate.htm