Translation - Portuguese brazilian-Latin - o óbvio só (somente) é óbvio para o olho...

literally: "pro oculo praeparato", but it doesn't sound good in Latin.
viri boni/homines boni

Bridge by lilian canale:
"Something obvious is obvious only for the eye which is prepared (ready to understand? )"

"Evil only prevails when good men keep quiet (don't act)"