If the poetic effects, that are produced as a within the plan of contents of a poem, can
create a certain climate or suggest a certain atmosphere, then it would be also correct to say, by
extending and taking advantage on a topologic metaphor, that the plan of expression constitutes
the very place from where poetic effects arise. Thus, the plan of expression constitutes some kind
of natural landscape for a poem. When we deal with the poetry from the Greco-Latin antiquity,
the poetic space has a quite well-delimited measuring tool, which is to say Metrics. This article
discusses some key-concepts by means of which certain ancient metricologists have considered
the nature, functionality and classification of some fundamental meters belonging to the old
Latin poetry.