Interesting that so many read this parable the wrong way. It’s not primarily about the seeds. It’s about the sower.
But, by the way:
“Therefore leaving the elementary teaching about the Christ, let us press on to maturity, not laying again a foundation of repentance from dead works and of faith toward God, of instruction about washings and laying on of hands, and the resurrection of the dead and eternal judgment. And this we will do, if God permits. For in the case of those who have once been enlightened and have tasted of the heavenly gift and have been made partakers of the Holy Spirit, and have tasted the good word of God and the powers of the age to come, and then have fallen away, it is impossible to renew them again to repentance, since they again crucify to themselves the Son of God and put Him to open shame.” (Hebrews 6:1-6)
Who are these that “have once been enlightened”? Do they even exist? Or is this a hypothetical situation that doesn’t ever actually happen? And if so, why is it here?