Mistérios translates to "mysteries." It's a captivating word that immediately sparks curiosity and suggests a deeper meaning within the song.
Milton Nascimento uses "mistérios" to refer to the profound, hidden knowledge of elements like fire, rivers, and the world itself. He expresses a desire to learn these mysteries to better understand and connect with his beloved, making it a central theme of the song's poetic exploration of love and nature.
"Mistérios" builds one image at a time: a fire, then a river, then a wind, each one moving through the singer and refusing to leave. "Um fogo queimou dentro de mim" ("a fire burned inside me") opens the song, and by the second verse it becomes "Um rio passou dentro de mim" ("a river passed through me"), then "Um vento bateu dentro de mim" ("a wind blew inside me") in the third. None of them can be put out, crossed, or held back, and each time the singer answers the same way: "Preciso aprender os mistérios do fogo" ("I need to learn the mysteries of the fire"), later "os mistérios do mundo" ("the mysteries of the world"), because loving someone means learning to read them like weather.
That line, repeated with small variations, is really the whole song. He isn't trying to win the person over with one big declaration. He's trying to learn them, patiently, the way you'd study a river before you cross it. Milton Nascimento sings it low and unhurried, so the final couplet, repeated twice at the end, doesn't land like a chorus hook. It sounds more like someone convincing himself: he still doesn't know how, but he's staying to find out.