Read the poem here: Aprensión
I started learning about blank verse earlier this month; in English, I realized that Shakespeare and Milton used it extensively in English, mostly in iambic pentameter. Its conversational, pensive tone seemed well suited for a lot of poems I had in mind, and I wondered how much it had been used in Spanish. As always, Borges showed me how its done with such masterful pieces as Un Sábado.
In Spanish it looks like we follow the Italian lead for this kind of verse, and instead of lines with five stresses and ten syllables, we're more eclectic: endecasílabos (hendecasyllables, eleven syllables), with all sorts of options for where to place the stresses and how to count the syllables—we have devices such as synaloepha or counting more or fewer syllables depending on where the tonic is on the last word (I found a very good reference on all of the foregoing in an obscure little academic piece).
I've tried to write a few blank verse pieces in both languages, with varying degrees of success, but one of the ones I feel worse about the least—despite the fact that there are quite a few lines where I didn't properly apply poetic licenses and thus have fewer syllables than eleven—is "Aprensión". I'll try to polish up a piece in English using this versification soon!