The disciples asked Jesus the meaning of The Parable of the Sower, because they knew it did not teach anything new concerning the sowing of seed. They knew it had a spiritual application, but they did not know what it was.

And He said to them, “Do you not understand this parable? How then will you understand all the parables?” (Mark 4.13).

He then proceeded to explain the parable. Once they could see the truth of that parable, their minds would open up more to understand the other parables.