This study explores the (co)relations between two measurable variables in poetry: the polarity of the verses, through sentiment analysis, and the metrical length of the same, using a computational routine for counting syllables based on the rules of Castilian versification. The corpus includes 15,153 poems by 1,114 Chilean poets from the 19th to the 21st centuries, representing diverse categories of sex, ethnicity, region and literary generation. The hypothesis suggests that minor art verses (<= 8 syllables) express light themes, while major art verses (>= 9 syllables) are associated with serious themes. The results, based on analyses of works that include Neruda, Mistral, Parra, Huidobro and De Rokha, show a significant negative evaluation.