What does Mark 4:4 mean?

Jesus' main parable in Mark 4 is about a farmer sowing seed in different types of soil. As he takes handfuls of seed, out of a basket or bag slung over his shoulder, and tosses them to the ground, some will inevitably land on the hard, sunbaked path. In his attempt to fully seed the fertile land, the farmer isn't stingy with his sowing. In order to get the biggest return, he will seed the land up to and over the paths that run along the sides of the fields.

Mark 4:15 explains that the seed scattered on the path and eaten by the birds represents when the gospel is preached to hard-hearted people who are easily influenced by Satan (1 Peter 5:8). Satan takes the words of truth from the minds of the unbelievers through lies or bitterness or false beliefs. Like the sower, we shouldn't reserve our preaching of the gospel, since we don't know where that metaphorical field ends and the hardened ground begins. There will be those who seem to be "on the edge" who do receive God's words.

Jesus deals with several different types of people in Mark 3, and here He explains why they react to Him the way they did. The seeds and the hard path represent those who already had hardened hearts toward Him. Their hearts weren't willing to accept His words, and Satan quickly ensured the words wouldn't stay long enough to work through the surface. This is reflected, in varying degrees, in the Pharisees and Herodians from Galilee (Mark 3:1–6) and the Pharisees who come from Jerusalem (Mark 3:22). Soon, they will be joined by the people from Jesus' hometown (Mark 6:1–6).