"This generation is an evil generation; it seeks a sign, but no sign will be given it, except the sign of Jonah. Just as Jonah became a sign to the Ninevites, so will the Son of Man be to this generation. (Lk 11,29-30)
We all need signs and symbols. Many things in the world are understood through signs and symbols. Sign is something that points to something higher. A gift given is a sign of affection or esteem. Values and higher realities are explained through signs.
Jesus’ life and works did raise many questions among the viewers and followers. They were wondering about him. Some believed in him, others questioned him, still others wondered whether Beelzebul was working in him etc.
Since there was no unanimity among the followers, people asked for signs as proofs. They asked for something specific to show that he was what he was.
Jesus did not give any sign as a proof. Jesus did not dance to their demands. However when people asked him in faith for miracles, cures etc he performed them. So whatever was asked for in faith then it was granted.
Here something was asked for as a proof then it was not granted. Signs were to be found in the realities of life and in the events of life. Jonah’s life was a proof and a sign.
Faith would find signs and proofs in miracles and extraordinary happenings but intellectual searches should find signs and proofs in realities, in events, and in persons who live or lived.