só háRoughly translated (losing some of its rhythm and meaning), it goes:
There is only
one thing [something]
do not know
something [one thing]
that no one
There are possibilities contained within these few short words. I bracketed [something] as "uma coisa" usually would be "something" but also could be "one thing," which offers dual interpretations in the original that does not exist in English; two separate words have to be used to denote possible interpretations. In one sense, the "one thing," there is a singular mystery that confounds narrator and others alike; in another, that mystery is more vague and non-specific, containing the possibility of other confounding elements.
This inherent impreciseness is what fascinates me, both as an occasional translator and as a poetry reader. The multiplicity implicit in these 14 words (or 16-18 in translation) lends itself to many reflections on what Bessa possibly meant here (not to mention that he himself might not know the various paths toward the approach to knowledge/understanding, which of course is a translation of the title). Doubtless there will be more thoughts that will come to me later, but for now, I am just content to share this with you.