When Jesus said blessed are the pure in heart, he was not talking about being naive and foolish. The Greek for pure is used elsewhere to mean clean after bathing (John 13:10). The Pharisees thought that they were righteous if they were clean on the outside (Matthew 23:26). Being clean or pure in the eyes of God begins on the inside. It has nothing to do with naivety and everything to do with innocence, being wise as serpents and harmless as doves. Their intent is for good and without pretense. They carry no malice or dishonesty in their hearts. How can the real world survive without such blessed people!