In its broad meaning, the word »poetry« can relate to anything that contains or conveys beauty and to the paroxystic pleasure associated with it, which may stand in for beauty itself. It is possible to compare wine (»This wine is poetry!«), a painting, or even a car and much more to poetry metaphorically, while the comparison turned around is either impossible or keeps the compared items logically separate: »This poetry is like wine.« This leads to the conclusion that poetry is essentially a matter of human perception of beauty.
Beauty is either »classical, objective«, or »sublime«. The former has set proportions and a static function which is not meant to be thought- or emotion-provoking but rather displays a decorative purpose. Temporally it belongs to the past and present, not to the future or to the possible. In spite of certain attempts, like the Parnassus movement in the 19th-century France, poetry is today not understood as an »objective« category. Who says »poetic«, means »sublime«.
The sublime is conveyed by suggestion, it is implied, not directly expressed. Only static objects, things, or whatever is treated like a thing, can be conveyed in a direct way. »Our love has come to an end« is, however, very different from Yeats's love »hid his face amid a crowd of stars«. It leaves the reader quite cold and unreceptive of the possible emotion behind such a sentence. Yeats's line is moving: this expression is ideal since movement is what defines human beings and life of which poetry partakes when it is sublime while anything that translates no movement burdens the memory in the best of cases as a monument (without derogating its importance).
Not anything that is »moving« is poetry or contains poetic elements though. Nature or TV News can only be »moving« or »poetic« by way of comparison, not in themselves. There are formal requirements constitutive of poetry like knowledge, intention and effort. The poetic form is a function of the poetic experience. The formal aspect of poetry (meter-rythm, rime, stanzaic patterns, of which some are required and some optional) or the insertion of poetic elements in genres of formally non-poetic nature are conventions that validate poetry.
Poetry can also be ironic, humoristic, »circumstantial«… but other genres assume these functions and often carry them out better than poetry. However, nothing but poetry can administer a brief shot of concentrated emotion that lingers on for years if it is authentic in terms of reception. Whatever we do, study, practice, work etc. can help us to come to grips with life in a better way than we used to. There are ways of coming to terms with ourselves and of accepting others, there are even methods for ethical self-improvement, indeed, for »making« ourselves what we want to be. Wherever we turn, there begins a path to follow, but nowhere do we see poetry. Poetry ineffably comes half way down each of these paths. It prepares us for the silence which comes at the end.