A path is only a path because the ground is trodden down by many feet.  Whatever its original purpose, the strip of hard soil is defined by the people (or animals) that repeatedly walk over it.  The result is an impervious surface which will not allow anything to grow.  Jesus used that analogy to describe people who hear God's Word but are unchanged by it.  The seed of truth has no chance to germinate because a resistant shell is around the person's heart (Matthew 13:15).

The devil has a special interest in encouraging people to become hard-hearted, because he can then snatch away the seeds of Truth.  But how do hearts become hard?  The picture of the path gives us a clue.  Over many years, probably from childhood, others have walked over their hearts until they actively choose to resist whatever comes to disturb their attempts to be in control of their own lives (Luke 11:52).  

Unwelcome circumstances dry out their capacity to respond appropriately to others, especially those in authority.  Such life stories suit Satan's purpose well in depriving these people of the only way to a new life.  Those who cooperate with the devil find that God allows them to have their own way, and He then finally hardens their hearts - as He did with Pharaoh (Exodus 7:13).  Jesus is clear.  These people will listen to the truth but refuse to obey it (Matthew 7:24-27).  God’s wrath is poured out, apparently allowing people to continue to defy God, but injuring themselves in the process (Romans 1:18-32; Hebrews 3:10-11).

What is the answer?  This parable simply diagnoses the problem without prescribing a remedy.  It taught the disciples to expect that some ministry will be apparently barren: but they must not be deflected by discouragement.  However, following the analogy, sometimes the cracks in the dried-out soil can provide lodging places where the Word can hide until the rain comes.  However hard the soil has become, God's Holy Spirit can soften the ground; so, it is no waste to 'sow' God's Word on the 'path' because if even a little gets hidden in the cracks, it will germinate when the rain comes. We do not know the outcome, but God always has the last word: to confirm the hardness or to show mercy (Romans 9:18).  Our task is to keep 'sowing' the Word; irrespective of what we think the outcome will be (2 Timothy 4:2-5).