Was a question that was asked by some Pharisees who were following the Lord Jesus. The Bible says in John 9:39-41, "And Jesus said, For judgment I am come into this world, that they which see not might see; and that they which see might be made blind. And some of the Pharisees which were with him heard these words, and said unto him, Are we blind also? Jesus said unto them, If ye were blind, ye should have no sin: but now ye say, We see; therefore your sin remaineth." I pray that we don't become like those Pharisees who were unaware that they were blind.
The Bible says in Romans 11:25, "For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in." To me, this gives a somewhat clearer understanding to what the Lord told those Pharisees that day. God, speaking through the prophet Isaiah said of Israel, "...Go, and tell this people, Hear ye indeed, but understand not; and see ye indeed, but perceive not. Make the heart of this people fat, and make their ears heavy, and shut their eyes; lest they see with their eyes, and hear with their ears, and understand with their heart, and convert, and be healed." (See Isaiah 6:9-10) It would almost seem that it was not God's intent that Israel was to be saved. But the Apostle Paul dealt with the seeming inconsistency in Romans 11:26 when he said, "And so all Israel shall be saved: as it is written, There shall come out of Sion the Deliverer, and shall turn away ungodliness from Jacob..." (You ought to take time to read chapter 11 of Romans in it's entirety to fully understand God's thoughts and ways concerning Israel).