Maraṇasati: Mindfulness of death
Keep death steadily in view. "As it happens to the fool, so will it happen even to me": the wise man's careful ledger and the fool's blank one are closed on the very same day, and the grave never pauses to read your accounts before it takes you. Holding that plainly, long before it is forced on you, is where a wise life should have started.
Anicca: Impermanence
Everything woven of time comes apart in time. Read "vanity" here as vapor, the breath you can see on a cold morning that thins and is gone before you finish looking at it, and close your hand on it and you hold nothing. Wisdom, wealth, the name you built all drift off as that same mist, so none of it can be banked against tomorrow.
Taṇhā: Craving
A thirst that reaches for more and for what lasts. "Why was I then more wise?" is that thirst counting its winnings and finding the purse empty, because wisdom was bought to secure an edge that keeps, a profit that death cannot cancel. Loosen the grip on that edge and the shared ending stays certain while the wound wrapped around it falls away.
Dukkha: Unsatisfactoriness
An ache hides inside anything you lean your weight on. Chase the finest wisdom and it still leaves the gnawing "why," the flat taste after a full meal that should have satisfied you and somehow did not, since being more wise only seasons the plate and never fills you. Everything here is asked to bear a weight past its strength, and it gives way.
Saṃvega: Urgent awakening
A cold jolt of urgency that turns a person toward the path. "Then I said in my heart that this also is vanity" fires like a starting gun, the instant the whole chase is seen as chasing vapor. Let it start you running toward what does not thin rather than drop you where you stand, for the heart that can sink this far is the same heart that can wake.