The present attempt to answer the question, What is poetry? has (a) delivered a minimal definition, (b) supplemented it with some prototypical features, and (c) called for historical articulation of the resulting complex. The first part of the essay reached an external and formal definition: a poem is a short text in verse. Following Werner Wolf’s attempt to distil prototypical features from a variety of earlier definitions, we concluded that besides textuality, brevity and verse, the characteristic features of lyric include a possibility of oral performance, deviation from everyday usage, a presence of unmediated consciousness, a subjective perspective, a foregrounding of the acoustic potential of verbal signifiers, a heightened self-referentiality and self-reflexivity, a relative lack of external action, absoluteness, and untranslatability. Although these features need not present themselves in each and every poem and they have many instances outside poetry, a prototypical poem – prototype being a mental construct for recognizing and classifying a given text as a poem – displays most of them. A possible prototypical poem may make some normative claims, even though deviations from the prototype may turn out to be aesthetically valuable as well. Addition of more evaluative features would result in a canonical poem. Poetry canons from various periods co-exist simultaneously in a given period as if revealed in a geological outcrop. Yet the canon is a cumulative and irreversible series rather than a synchronic simultaneous agglomerate, although the sense of the historicity of the canon seems to be receding. It is hoped that the prototypical features listed would enable an empirical specification and study of canons inhabiting Estonian culture at a given time.