So think of it this way if you will.
The sees are alive because God inhabits his word. The sower is the evangelist, or person sharing the gospel to his neighbor. So he broadcasts the seeds, and Jesus compares the different hearers of this living word inhabited by God through his Holy Spirit. This word enters the man and calls him to repentance and empowers him to repent because he has no ability to, but some men are hard hearted and reject this grace, immediately. He by his will gardens himself against this word. Then there is the man who received the word and likes what he hears and at first he doesn't reject right away but when he walks away he become indulged in his life hardening himself against the grace given him, thus he is not converted because he rejects God's word and the conviction of the Holy Spirit, now the third man is convicted by those words and believes and he is broken by the weight of his sins and tenderized, and his will gives way and he is converted. Not by his strength but because he is weak, and the Holy Spirit converts him and he is reborn.