'Understood' in the Bible

None of the rulers of this age understood it. If they had known it, they would not have crucified the Lord of glory.

The one who is spiritual discerns all things, yet he himself is understood by no one.

It is similar for lifeless things that make a sound, like a flute or harp. Unless they make a distinction in the notes, how can what is played on the flute or harp be understood?