"When anyone hears the word of the kingdom and does not understand it, the evil one comes and snatches away what is sown in the heart; this is what was sown on the path."

If the devil snatches away the word which is sown in the heart is it not the good angels who place God's word there?  Those lose that most precious of all seeds to the devil who do not understand that which is given.  This is entirely their own fault, as the Lord had just stated prior to the explanation of this parable: you will never understand if your heart has grown dull, your ears hard of hearing and your eyes closed.  Thus the seed of the Word is seen as commonplace, of no special significance, not relevant to today, not able to speak to the heart and lacking in power to completely transform one's life.

In contrast, meditate on the example of the Ethiopian eunuch.  He was studiously reading one of the messianic prophecies of Isaiah and inwardly longing to know the hidden mysteries contained therein.  See with what swiftness God dispatched his angel to Philip who in turn was sent quickly to the eunuch.  "Do you understand what you are reading?" he asked, then proceeded from this scripture to proclaim the good news about Jesus.  So inflamed was the eunuchs heart that he immediately had his chariot stopped by some water so he could become baptized.  Mission accomplished, Philip was snatched away and can there be any doubt that henceforth the eunuch enjoyed a life-long relationship with the Word. (Acts 8.26-39)

All roads in scripture lead to the gospel of Christ and he is ever zealous to send out one choir's angels to sow his holy word in us.  It is up to us to "hold it fast in an honest and good heart, and bear fruit with patient endurance," (Luke 8.15) trusting that he will dispatch angels from another choir to help us understand the deep mysteries of the kingdom.

The bad angels try to place seeds in us also: of remembrance of past injuries received, our self-interests, our rights, our ego...