This is very similar to Jesus' explanation of parables. God says He scatters understanding on any given subject throughout the Bible, and our job is to put it all together and see the amazing truth that results. Therefore, parables cannot be interpreted alone; they rely on the revelation of the rest of Scripture.
Christ did not speak in parables to make the meaning clear to just any reader! From the very beginning, God has supervised the writing of the Bible so that it cannot be understood without outside help. Even prophets and righteous men of old did not understand, nor did the multitudes who heard the parables of Christ. According to Romans 11, the meaning is veiled from most of mankind until the day God offers them salvation. They are relegated to unbelief until a later time (i.e. the Millennium or Great White Throne Judgment), lest they rebel and must be destroyed.
