Buddhist traditions summarize three characteristics: impermanence (anicca), dukkha, and not-self (anattā). The Dhammapada states that all conditioned things are impermanent, all conditioned things are dukkha, and all Dhammas are not-self. The wording is precise: Nibbāna is not conditioned and is not called dukkha, yet even Nibbāna is not to be claimed as a self.
Impermanence is more than the observation that old objects break. Whatever arises due to conditions ceases when those conditions change. Bodies, feelings, perceptions, intentions, states of concentration, heavenly lives, institutions, and worlds are included. Insight observes arising and passing closely enough that the mind stops expecting a conditioned state to provide permanent refuge.
Dukkha follows because what is unstable cannot be held on our terms. Pleasant experience is pleasant, but clinging turns its change into distress. Painful experience already hurts, and clinging adds resistance and identity. Neutral experience easily supports ignorance. The characteristic does not deny joy; it reveals why conditioned joy is not final liberation.
Not-self means that phenomena are not fit to be regarded as "This is mine, this I am, this is my self." It is not the claim that no actions or persons exist conventionally. The teaching analyzes experience so that ownership and identification weaken. The five aggregates lesson will examine this more closely.
The three characteristics form a single insight sequence. What is impermanent and vulnerable to change cannot reliably satisfy; what is impermanent, unsatisfactory under clinging, and not controllable should not be appropriated as an eternal self. Seeing this repeatedly produces disenchantment, fading of passion, release, and knowledge of release.
The Buddha compares form to foam on a river, feeling to a bubble, perception to a mirage, volitional formations to a plantain trunk with no heartwood, and consciousness to a magic trick. Examined closely, none offers a solid core to grasp.
In a famous later story, the grieving Kisā Gotamī asks the Buddha to restore her dead child. He asks for mustard seeds from a house untouched by death. Going door to door, she discovers that every family has lost someone and begins to understand the universality of death.